# Boeing Alert Service Bulletin 737-78A1099: No revision named - Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2026-2726, the docket of a proposed AD (Federal Register 2026-06067). Not covered by OpenAirDocs’ CC0 dedication. - Document: [Boeing Alert Service Bulletin 737-78A1099](https://openairdocs.org/service-documents/boeing/737-78a1099.md) - Title as filed: SB-737-78A1099-00-RB - Pages: 70 - PDF: https://openairdocs.org/files/sha256/a5/7c/a57cb4b51ad313f95e7bddbb306b6bdd7b9f6c84369e9013732661479af37dea - Page: https://openairdocs.org/service-documents/boeing/737-78a1099/file/a57cb4b51ad3 ## Text Some pages are OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 Commercial Airplanes 737 Requirements Bulletin ALERT Number: 737-78A1099 RB Original Issue: July 08, 2025 ATA System: 7831 SUBJECT: EXHAUST (CFM56 Engines (CFM56-7)) - Thrust Reverser System - Upper Locking Hydraulic Actuators Proximity Sensor Target Inspection EXPORT CONTROLLED - This technology or software is subject to the U.S. Export Administration Regulations (EAR), (15 C.F.R. Parts 730-774). No authorization from the U.S. Department of Commerce is required for export, re-export, in-country transfer, or access EXCEPT to country group E:1 or E:2 countries/persons per Supp.1 to Part 740 of the EAR. 9E991ECCN: Copyright © 2025 The Boeing Company Treatment of this document and its content is governed by contract with Boeing. Rights to use this document are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The Boeing Company. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing. Original Issue: July 08, 2025 737-78A1099 RB 1 of 70 8.0 ### Page 2 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 2 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT BLANK PAGE ### Page 3 Table of Contents 1. EFFECTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 A. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 B. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2. CONCURRENT REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3. COMPLIANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4. APPROVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 A. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 B. Work Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 FIGURE 1: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) MANUAL UNLOCK HANDLE ASSEMBLY ANGULAR FREE-PLAY MEASUREMENT (RELATED TO PROCEDURE 1) . . . . . . . . . . . . . . . . . . . . . 45 FIGURE 2: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) MANUAL UNLOCK HANDLE ASSEMBLY ANGULAR FREE-PLAY MEASUREMENT (RELATED TO PROCEDURE 1) . . . . . . . . . . . . . . 47 FIGURE 3: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR MANUAL UNLOCK HANDLE ASSEMBLY TORSION SPRING OPERATIONAL CHECK (RELATED TO PROCEDURE 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 FIGURE 4: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 FIGURE 5: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 FIGURE 6: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR TARGET MEASUREMENT (RELATED TO PROCEDURE 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 FIGURE 7: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) PROXIMITY SENSOR TARGET MEASUREMENT (RELATED TO PROCEDURE 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 APPENDIX A: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR INTEGRITY TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 3 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 4 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 4 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT BLANK PAGE ### Page 5 Commercial Airplanes 737 Requirements Bulletin ALERT Number: 737-78A1099 RB Original Issue: July 08, 2025 ATA System: 7831 SUBJECT: EXHAUST (CFM56 Engines (CFM56-7)) - Thrust Reverser System - Upper Locking Hydraulic Actuators Proximity Sensor Target Inspection THIS DOCUMENT IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS DOCUMENT TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS DOCUMENT TO THE NEW OWNER. THIS IS AN ENHANCED REQUIRED FOR COMPLIANCE DOCUMENT. THE BOEING PROCESSES USED TO CREATE THE SERVICE BULLETIN (SB) AND THE REQUIREMENTS BULLETIN (RB) ENSURE THAT THE INFORMATION BETWEEN "RC START" AND "RC END" IN THE SB ARE IDENTICAL TO THE INFORMATION IN THE SAME SECTIONS (COMPLIANCE, WORK INSTRUCTIONS…) OF THE RB WHICH THE SB REFERS TO AS THE RELATED DOCUMENT. 1. Effectivity A. Airplanes This bulletin is applicable to 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER Airplane(s), line number(s) 1-2598, 2600-2721, 2723-2813, 2815-2930, 2932-3068, 3070-3323, 3325-3425, 3427-3521, 3523-3611, 3613-3701, 3703-3791, 3793-3878, 3880-3915, 3917-3968, 3970-4013, 4015-4054, 4056-4098, 4100-4140, 4142-4180, 4182-4218, 4220-4255, 4257-4293, 4295-4330, 4332-4365, 4367-4398, 4400-4444, 4446-4480, 4482-4546, 4548-4608, 4610-4672, 4674-4727, 4729-4767, 4769-4812, 4814-4858, 4860-4897, 4899-4937, 4939-4977, 4979-5019, 5021-5057, 5059-5097, 5099-5137, 5139-5177, 5179-5217, 5219-5261, 5263-5297, 5299-5337, 5339-5367, 5369-5397, 5399-5427, 5429-5457, 5459-5477, 5479-5509, 5511-5541, 5543-5566, 5568-5586, 5588-5601, 5603-5622, 5624-5655, 5657-5667, 5669-5679, 5681-5711, 5713-5727, 5729-5739, 5741-5764, 5766-5787, 5789-5795, 5797-5822, 5824-5850, 5853-5879, 5881-5901, 5904-5935, 5937-5947, 5949-5962, 5964-5991, 5994-6019, 6021-6033, 6035-6047, 6049-6073, 6075, 6077-6103, 6105-6113, 6115-6131, 6133-6153, 6155-6159, 6161-6187, 6190-6215, 6217-6221, 6223-6243, 6245-6249, 6251-6271, 6274-6289, 6291-6299, 6301-6307, 6309-6325, 6327, 6329-6343, 6345-6355, 6357-6359, 6361-6371, 6373-6383, 6386-6395, 6397-6407, 6409-6411, 6413-6419, 6421-6429, 6431-6439, 6442-6447, 6449-6455, 6457-6463, 6465-6467, 6469-6471, 6473-6480, 6482-6489, 6491, 6493-6498, 6500-6507, 6509-6514, 6516-6520, 6522-6527, 6529-6531, 6533-6534, 6536-6541, 6543-6547, 6549-6554, 6556-6559, 6561, 6563-6568, 6570-6574, 6576-6581, 6583-6588, 6590-6593, 6596-6597, 6599-6602, 6604-6606, 6608-6611, 6613-6615, 6617-6620, 6622, 6624, 6626-6629, 6631-6633, 6635-6638, 6640-6642, 6644-6647, 6649-6651, 6653-6656, 6659-6660, 6662-6665, 6667-6671, 6673-6676, 6678-6680, 6682-6685, 6688-6689, 6691-6694, 6696-6698, 6700-6703, 6705-6707, 6709-6712, 6714-6716, 6718-6719, 6721, 6723-6725, 6727-6730, 6732-6734, 6736-6739, 6741-6743, 6745-6748, 6751-6752, 6754-6757, 6759-6761, 6763-6766, 6768-6770, 6772-6775, 6777-6779, 6781-6782, 6786-6788, 6790-6791, 6793, 6795, 6797, 6799-6802, 6804, 6806, 6808-6809, 6811, 6813, 6815, 6817-6818, 6820, 6822-6824, 6826-6827, 6829, 6831-6833, 6835-6836, 6838, 6840, 6842, 6844-6845, 6847, 6849, 6851, 6853-6854, 6856-6858, 6860, 6862-6863, 6865, 6867, 6869-6871, Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 5 of 70 ### Page 6 6873-6874, 6878-6880, 6882-6883, 6885, 6887-6889, 6891-6892, 6894, 6896, 6898, 6900-6903, 6905, 6907, 6910, 6912-6914, 6916, 6918-6919, 6921, 6923-6925, 6927-6928, 6930, 6932-6934, 6936-6937, 6939, 6943, 6945-6948, 6950, 6952, 6954-6955, 6957-6959, 6961-6962, 6964, 6966-6967, 6969, 6971-6972, 6977, 6979, 6981-6982, 6984, 6986-6987, 6989, 6992, 6994, 6996-6997, 6999, 7001-7002, 7007, 7009, 7011-7012, 7014, 7016-7017, 7019, 7021-7022, 7024, 7026, 7029, 7031-7032, 7034, 7036-7037, 7039, 7041, 7046-7047, 7049, 7051-7052, 7054, 7056-7057, 7059, 7061, 7063, 7066-7067, 7069, 7071-7072, 7076, 7078, 7081-7082, 7084, 7086-7087, 7089, 7091-7092, 7094, 7097, 7099, 7101-7102, 7104, 7106-7107, 7109, 7112, 7116-7117, 7119, 7121-7122, 7124, 7126-7127, 7129, 7131, 7134, 7136-7137, 7139, 7141-7142, 7146, 7149, 7151-7152, 7154, 7156-7157, 7159, 7161-7162, 7164, 7167, 7169, 7171-7172, 7174, 7176-7177, 7179, 7182, 7187, 7189, 7191, 7194, 7197, 7199, 7202, 7204, 7206, 7209, 7212, 7214, 7217, 7221, 7224, 7227, 7229, 7232, 7234-7235, 7239, 7242, 7244, 7247, 7249, 7251, 7257, 7259, 7262, 7264, 7266, 7269, 7272, 7274, 7277, 7279-7280, 7284, 7287, 7292, 7294, 7297, 7299, 7302, 7304, 7307, 7309, 7312, 7314, 7317, 7319, 7322, 7327, 7329, 7332, 7334, 7337, 7339, 7342, 7344, 7347, 7349, 7352, 7354, 7357, 7362, 7364, 7367, 7369, 7372, 7374, 7377, 7379, 7382, 7387, 7397, 7402, 7407, 7412, 7417, 7422, 7432, 7437, 7442, 7447, 7452, 7457, 7467, 7472, 7477, 7482, 7487, 7492, 7502, 7507, 7512, 7517, 7522, 7527, 7537, 7547, 7552, 7557, 7562, 7572, 7577, 7582, 7587, 7592, 7597, 8592, 9103, 9274, 9430-99999 in 1 Group(s). Where the effectivity is presented with hyphens between line numbers, the airplane applicability means "through" and "inclusive", e.g. line numbers 1-9 means line numbers 1 through 9 inclusive. The Variable Numbers and Group Information for the applicable airplanes is given below. NOTE: The Variable Number table below includes affected airplanes available as of the issue date of this bulletin. Affected airplane Variable Numbers added to MyBoeingFleet.com after the issue date of this bulletin will be shown using the Maintenance Performance Toolbox EFFECTIVITY search function result. DESCRIPTIONCONFIGURATIONGROUP All 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER Airplanes. -1 Airplane Models: 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER GroupVariable Number 1YA001 - YA099 1YA101 - YA199 1YA201 - YA211 1YA221 1YA231 - YA242 1YA251 - YA256 1YA271 - YA272 GroupVariable Number 1YA291 1YA301 - YA302 1YA311 - YA314 1YA321 - YA323 1YA336 - YA345 1YA351 1YA356 - YA357 GroupVariable Number 1YA366 - YA367 1YA371 - YA377 1YA501 - YA536 1YA541 - YA552 1YA571 - YA578 1YA601 - YA615 1YA621 - YA622 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 6 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 7 GroupVariable Number 1YA626 - YA631 1YA635 - YA636 1YA641 - YA642 1YA645 - YA650 1YA656 - YA659 1YA666 - YA667 1YA671 - YA672 1YA681 - YA691 1YA701 - YA710 1YA721 - YA722 1YA731 - YA734 1YA751 - YA756 1YA801 - YA803 1YA809 1YA811 - YA814 1YA831 - YA835 1YA841 - YA862 1YA881 - YA882 1YA891 - YA892 1YA961 - YA978 1YB001 - YB006 1YB101 - YB132 1YB151 - YB153 1YB156 - YB158 1YB161 - YB164 1YB171 - YB172 1YB181 - YB184 1YB201 - YB208 1YB271 1YB276 1YB301 - YB310 1YB371 - YB392 1YB501 - YB502 GroupVariable Number 1YB521 - YB526 1YB541 - YB544 1YB551 1YB561 - YB598 1YB601 - YB636 1YB651 1YB656 1YB671 - YB672 1YB851 - YB863 1YB871 - YB874 1YB881 - YB893 1YB901 - YB903 1YB911 1YB961 - YB975 1YB981 1YB986 - YB998 1YC001 - YC030 1YC051 - YC084 1YC091 - YC095 1YC101 - YC104 1YC111 - YC113 1YC121 1YC126 - YC127 1YC136 - YC141 1YC146 - YC147 1YC151 - YC156 1YC166 - YC171 1YC176 - YC179 1YC186 - YC190 1YC201 - YC203 1YC206 - YC207 1YC301 - YC305 1YC321 - YC387 GroupVariable Number 1YC391 - YC394 1YC396 1YC401 - YC417 1YC421 - YC422 1YC426 - YC428 1YC436 - YC439 1YC441 - YC448 1YC451 - YC455 1YC459 1YC461 - YC467 1YC471 - YC499 1YC501 - YC526 1YC571 - YC583 1YC587 - YC589 1YC591 - YC593 1YC601 - YC655 1YC681 - YC696 1YC701 - YC715 1YC720 - YC725 1YC727 - YC752 1YC761 - YC770 1YC781 - YC793 1YC801 - YC892 1YC901 - YC907 1YC921 - YC922 1YC931 - YC932 1YC941 - YC951 1YC971 - YC978 1YC981 - YC983 1YD001 - YD007 1YD021 - YD025 1YD041 - YD057 1YD081 - YD084 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 7 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 8 GroupVariable Number 1YD101 - YD117 1YD121 - YD126 1YD151 - YD159 1YD171 - YD172 1YD201 - YD203 1YD206 - YD209 1YD216 - YD219 1YD251 - YD254 1YD256 - YD257 1YD261 1YD301 - YD334 1YD391 1YD401 - YD410 1YD412 - YD424 1YD481 - YD485 1YD491 - YD499 1YD501 - YD512 1YD531 - YD535 1YD541 - YD547 1YD561 - YD564 1YD571 - YD572 1YD591 - YD595 1YD601 - YD612 1YD651 - YD655 1YE001 - YE020 1YE051 1YE101 - YE109 1YE151 - YE157 1YE171 - YE172 1YE201 - YE206 1YE301 - YE305 1YE321 - YE326 1YE371 - YE383 GroupVariable Number 1YF001 - YF011 1YF021 - YF049 1YF051 - YF080 1YF086 - YF087 1YF106 - YF107 1YF111 - YF114 1YF116 - YF119 1YF121 - YF132 1YF176 - YF178 1YF191 - YF192 1YF201 - YF276 1YF401 - YF402 1YF431 - YF432 1YF436 - YF437 1YF441 - YF442 1YF451 - YF460 1YF501 - YF599 1YF601 - YF685 1YF691 - YF695 1YF701 - YF707 1YF801 - YF805 1YF831 - YF832 1YF836 - YF838 1YF871 - YF872 1YF901 - YF905 1YF921 - YF928 1YF951 - YF954 1YG001 - YG044 1YG061 - YG064 1YG066 - YG089 1YG091 - YG099 1YG101 - YG104 1YG111 - YG114 GroupVariable Number 1YG116 - YG149 1YG151 - YG152 1YG201 - YG205 1YG211 - YG214 1YG221 - YG224 1YG251 - YG252 1YG501 - YG517 1YG601 - YG602 1YG701 1YG711 1YG721 - YG722 1YH001 - YH012 1YH031 - YH055 1YH071 - YH080 1YH101 - YH132 1YH201 - YH202 1YH206 - YH207 1YH301 - YH307 1YH321 - YH322 1YH501 - YH542 1YH551 - YH594 1YH601 - YH606 1YH611 - YH620 1YH631 - YH632 1YH636 - YH637 1YH641 1YH681 - YH686 1YH701 - YH755 1YH801 - YH899 1YH901 - YH908 1YH911 - YH915 1YH951 - YH952 1YJ001 - YJ013 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 8 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 9 GroupVariable Number 1YJ021 1YJ471 - YJ480 1YJ501 - YJ517 1YJ531 - YJ579 1YJ591 - YJ599 1YJ631 - YJ632 1YJ671 - YJ694 1YJ801 - YJ867 1YJ871 - YJ880 1YJ901 - YJ904 1YJ908 - YJ929 1YJ931 - YJ937 1YJ941 - YJ956 1YJ961 1YJ976 - YJ977 1YK001 - YK007 1YK101 - YK104 1YK111 - YK112 1YK121 - YK122 1YK131 - YK133 1YK136 - YK139 1YK141 - YK142 1YK146 - YK148 1YK151 - YK154 1YK161 - YK167 1YK171 1YK176 - YK177 1YK186 1YK191 1YK196 1YK201 - YK202 1YK301 - YK314 1YK321 - YK340 GroupVariable Number 1YK361 - YK378 1YK401 - YK406 1YK426 - YK427 1YK431 - YK450 1YK456 - YK467 1YK471 - YK473 1YK476 1YK478 1YK480 - YK487 1YK491 - YK493 1YK495 - YK499 1YK511 - YK516 1YK521 - YK530 1YK551 - YK571 1YK576 - YK577 1YK580 - YK585 1YK601 - YK602 1YK606 - YK607 1YK611 - YK616 1YK621 - YK634 1YK641 - YK644 1YK651 - YK665 1YK671 - YK672 1YK676 - YK677 1YK681 - YK686 1YK691 1YK695 - YK699 1YK701 - YK713 1YK716 - YK719 1YK721 - YK741 1YK751 - YK770 1YK776 - YK778 1YK781 - YK785 GroupVariable Number 1YK791 - YK792 1YK796 - YK797 1YK801 - YK899 1YK901 - YK912 1YK918 - YK919 1YK921 - YK929 1YK941 - YK999 1YL001 - YL005 1YL011 - YL016 1YL021 - YL024 1YL051 - YL052 1YL056 - YL057 1YL061 1YL066 - YL069 1YL076 - YL077 1YL101 - YL137 1YL201 - YL237 1YL241 - YL242 1YL271 - YL272 1YL281 - YL284 1YL301 - YL303 1YL311 - YL314 1YL316 - YL321 1YL351 - YL353 1YL371 - YL374 1YL401 1YL421 - YL429 1YL431 - YL444 1YL461 - YL478 1YL501 - YL509 1YL531 - YL534 1YL541 - YL551 1YL561 - YL579 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 9 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 10 GroupVariable Number 1YL591 - YL598 1YL601 - YL606 1YL611 - YL612 1YL616 - YL617 1YL621 1YL626 1YL631 - YL634 1YL636 - YL637 1YL661 - YL664 1YL676 - YL691 1YL696 - YL697 1YL701 - YL707 1YL731 1YL751 - YL752 1YL756 - YL757 1YL761 - YL780 1YL796 - YL797 1YL801 - YL815 1YL901 - YL910 1YL921 - YL940 1YL951 - YL968 1YM101 - YM103 1YM201 - YM244 1YM251 - YM299 1YM301 - YM399 1YM401 - YM415 1YM471 1YM481 - YM484 1YM501 - YM515 1YM521 - YM522 1YM541 1YM551 - YM553 1YM571 - YM572 GroupVariable Number 1YM581 - YM582 1YM591 - YM599 1YM631 - YM634 1YM641 - YM652 1YM671 - YM674 1YM691 - YM699 1YM701 - YM710 1YM761 - YM765 1YM771 - YM779 1YN001 - YN016 1YN021 - YN024 1YN061 1YN071 - YN082 1YN091 - YN092 1YN101 - YN112 1YN121 1YN126 1YN201 - YN202 1YN211 - YN219 1YN231 - YN236 1YN261 1YN501 1YN531 - YN534 1YN551 - YN566 1YN581 - YN585 1YN591 - YN593 1YN601 - YN606 1YN651 - YN653 1YN661 - YN663 1YN666 - YN667 1YN671 - YN674 1YN701 - YN702 1YN741 - YN746 GroupVariable Number 1YN756 - YN758 1YQ001 - YQ003 1YQ011 - YQ021 1YQ026 - YQ029 1YQ036 - YQ045 1YQ201 - YQ207 1YQ231 1YQ241 - YQ251 1YQ281 - YQ284 1YQ291 - YQ296 1YQ301 - YQ302 1YQ321 - YQ324 1YQ331 - YQ334 1YQ346 - YQ347 1YQ351 - YQ367 1YQ371 1YQ401 - YQ403 1YQ451 - YQ454 1YQ456 1YQ461 1YQ471 1YQ501 - YQ520 1YQ601 - YQ606 1YQ610 - YQ614 1YR001 - YR098 1YR101 - YR105 1YR111 - YR124 1YR126 - YR144 1YR166 - YR182 1YR186 - YR198 1YR201 - YR215 1YR231 - YR294 1YR296 - YR297 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 10 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 11 GroupVariable Number 1YR301 - YR334 1YR338 - YR341 1YR361 - YR366 1YR371 - YR373 1YR376 - YR377 1YR381 - YR382 1YR386 - YR388 1YR391 1YR396 - YR399 1YR401 - YR405 1YR411 - YR413 1YR416 - YR418 1YR421 - YR424 1YR426 - YR455 1YR457 - YR499 1YR501 - YR506 1YR511 - YR520 1YR526 - YR544 1YR546 - YR551 1YR556 - YR562 1YR571 - YR582 1YR591 - YR592 1YR601 - YR605 1YR616 - YR658 1YR661 - YR663 1YR671 - YR673 1YR676 - YR678 1YR681 - YR682 1YR701 - YR769 1YR771 - YR799 1YR801 - YR827 1YR831 - YR838 1YR841 - YR899 GroupVariable Number 1YR901 - YR903 1YR931 - YR934 1YR938 - YR944 1YR951 - YR998 1YS001 - YS002 1YS006 - YS009 1YS031 - YS032 1YS051 - YS073 1YS101 - YS120 1YS126 - YS142 1YS146 - YS160 1YS166 - YS194 1YS196 - YS197 1YS201 - YS209 1YS221 - YS225 1YS231 - YS236 1YS271 - YS288 1YS295 - YS296 1YS301 - YS348 1YS351 - YS378 1YS381 - YS386 1YS393 - YS395 1YS401 1YS451 1YS456 - YS457 1YS462 - YS465 1YS467 1YS501 - YS502 1YS506 1YS511 - YS518 1YS531 1YS536 - YS538 1YS541 - YS542 GroupVariable Number 1YS546 1YS551 - YS556 1YS561 - YS578 1YS581 - YS595 1YS601 - YS690 1YS701 - YS716 1YS721 - YS762 1YS771 - YS780 1YS806 - YS810 1YS816 - YS818 1YS823 - YS825 1YS851 - YS863 1YS876 1YS881 - YS884 1YS891 - YS894 1YS896 - YS897 1YS901 - YS909 1YS911 - YS957 1YS961 - YS974 1YS976 - YS977 1YS981 - YS987 1YS991 - YS998 1YT001 - YT004 1YT006 1YT026 - YT027 1YT031 - YT032 1YT036 - YT038 1YT061 - YT068 1YT101 - YT138 1YT176 - YT185 1YT191 1YT196 - YT199 1YT201 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 11 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 12 GroupVariable Number 1YT206 - YT207 1YT211 - YT213 1YT251 - YT299 1YT301 - YT307 1YT311 - YT312 1YT321 - YT355 1YT371 - YT372 1YT381 1YT391 - YT396 1YT401 - YT403 1YT411 - YT417 1YT427 1YT461 - YT477 1YT491 - YT492 1YT501 - YT521 1YT551 - YT552 1YT556 - YT563 1YT565 1YT571 - YT578 1YT601 - YT606 1YT701 - YT708 1YT723 - YT726 1YT761 - YT781 1YT791 - YT794 1YT796 - YT797 1YT801 - YT804 1YT811 - YT813 1YT826 - YT827 1YT831 - YT832 1YT841 - YT852 1YT856 - YT863 1YT885 - YT887 1YT891 - YT895 GroupVariable Number 1YT901 - YT998 1YU001 - YU060 1YU201 - YU218 1YU301 - YU329 1YU901 - YU931 1YV001 - YV012 1YV021 - YV023 1YV030 - YV034 1YV037 - YV042 1YV045 - YV047 1YV051 - YV059 1YV081 1YV083 - YV084 1YV097 - YV099 1YV101 - YV154 1YV201 - YV203 1YV251 - YV252 1YV256 - YV257 1YV301 - YV312 1YV351 - YV368 1YV381 - YV388 1YV391 - YV394 1YV401 1YV411 - YV413 1YV431 - YV433 1YV441 - YV454 1YV461 - YV464 1YV467 - YV470 1YV501 - YV512 1YV521 1YV571 - YV586 1YV596 1YV601 - YV605 GroupVariable Number 1YV651 - YV674 1YV676 1YV695 - YV696 1YV701 - YV702 1YV711 1YV722 - YV731 1YV741 - YV794 1YV801 - YV820 1YV831 - YV848 1YV881 - YV883 1YV901 - YV915 1YV923 - YV926 1YV971 - YV983 1YW001 1YW011 - YW099 1YW101 - YW164 1YW201 - YW212 1YW226 - YW240 1YW245 - YW261 1YW263 1YW267 - YW281 1YW283 - YW285 1YW292 - YW299 1YW351 1YW356 - YW358 1YW361 - YW366 1YW371 - YW399 1YW401 - YW430 1YW441 - YW445 1YW451 - YW452 1YW471 - YW472 1YW491 - YW498 1YW531 - YW536 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 12 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 13 GroupVariable Number 1YW541 - YW545 1YW551 - YW580 1YW585 - YW591 1YW595 - YW596 1YW601 1YW610 - YW613 1YW616 - YW623 1YW666 GroupVariable Number 1YW696 - YW699 1YW701 - YW715 1YW726 - YW731 1YW766 - YW775 1YW801 - YW803 1YW811 - YW813 1YW821 1YW831 GroupVariable Number 1YW881 1YW891 - YW893 1YW906 - YW910 1YW916 - YW918 1YW921 - YW925 1YW971 - YW976 -- -- B. Spares Affected None. 2. CONCURRENT REQUIREMENTS None. 3. COMPLIANCE Federal Aviation Administration (FAA) Airworthiness Directive AD 2019-18-03 is related to this service bulletin. The effective date of AD 2019-18-03 is October 3, 2019. The Federal Aviation Administration (FAA) will possibly release an additional Airworthiness Directive related to Requirements Bulletin 737-78A1099 RB. The Airworthiness Directive will make the compliance tasks and times given in Requirements Bulletin 737-78A1099 RB mandatory. Accomplish the required action(s), based on the applicable condition(s) in Tables 2 through 11, inclusively in accordance with Accomplishment Instructions. When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When more than one ACTION is given for a CONDITION or an OPTION, do all of the ACTION numbers for that CONDITION or OPTION. Table 1: Upper Locking Hydraulic Actuator Procedure Description and Satisfactory Procedure Result Definition Procedure Result - Satisfactory Defi- nition DescriptionProcedure Number Thrust Reverser Upper Locking Hy- draulic Actuator Manual Unlock Handle Assembly angular free-play is less than or equal to 9.40 degrees. Measurement of the Upper Locking Hy- draulic Actuator Manual Unlock Handle Assembly angular free-play. Procedure 1 (a) Thrust Reverser Sleeve stays in the fully stowed position as specified in Appendix A. Test of the integrity of the Upper Locking Hydraulic Actuator to find if the Thrust Reverser Sleeve stays in the fully stowed position. Procedure 2 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 13 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 14 Table 1: Upper Locking Hydraulic Actuator Procedure Description and Satisfactory Procedure Result Definition Procedure Result - Satisfactory Defi- nition DescriptionProcedure Number Thrust Reverser Upper Locking Hy- draulic Actuator Manual Unlock Handle Assembly returns to its initial position. Operational check of the Upper Locking Hydraulic Actuator Manual Unlock Han- dle Assembly Torsion Spring. Procedure 3 (a) Thrust Reverser Upper Locking Hy- draulic Actuator distance between the center of the Proximity Sensor and Proximity Sensor Target Leading Edge is within 0.33 and 0.37 inches, inclusive- ly. Measurement of the clearance between the Upper Locking Hydraulic Actuator Proximity Sensor and Proximity Sensor Target Leading Edge. Procedure 4 – Upper Locking Hydraulic Actuator (Part Number (P/N) 315A2801-1) Proximity Sensor Target dimension 'A' and dimension 'B' is within 1.089 and 1.111 inches, inclusively. – Upper Locking Hydraulic Actuator (P/N 315A2801-4 or P/N 315A2801- 5) Proximity Sensor Target dimen- sion 'A' is within 0.949 and 0.971 inches, inclusively and dimension 'B' is within 0.789 and 0.811 inches, inclusively. Measurement of the Upper Locking Hy- draulic Actuator Proximity Sensor Tar- get. Procedure 5 (a) (a) This Procedure may be done off wing. Table 2: Engine 1 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Whichever occurs later:Do Procedure 1. (a)(b)All Airplanes 1. Within 24 months af- ter the original issue date of Requirements Bulletin 737-78A1099 RB. Do Procedure 2. (a)(b) Do Procedure 3. (a)(b) Do Procedure 4. (a)(b) Do Procedure 5. (a)(b) 2. Within 24 months af- ter the date of issuance of the original standard certificate of airworthi- ness or the original ex- port certificate of airwor- thiness. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 14 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 15 Table 2: Engine 1 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition --No further action is required.CONDITION 1: LEFT AND RIGHT UPPER LOCKING HY- DRAULIC ACTUATORS' PRO- CEDURE 1, PROCEDURE 2, PROCEDURE 3, PROCEDURE 4, AND PROCEDURE 5 RE- SULTS ARE SATISFACTORY. -At the times specified in Table 3. Do Upper Locking Hydraulic Actua- tor Replacement specified in Table 3. CONDITION 2: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. -At the times specified in Table 4. Do Upper Locking Hydraulic Actua- tor Spring Replacement or Upper Locking Hydraulic Actuator Replace- ment specified in Table 4. CONDITION 3: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. -At the times specified in Table 5. Do Upper Locking Hydraulic Actua- tor Proximity Sensor Target Re- placement or Upper Locking Hy- draulic Actuator Replacement specified in Table 5. CONDITION 4: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 15 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 16 Table 3: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Replacement Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.(OPTION 1) (ACTION 1): Deacti- vate the thrust reverser for flight. Any Upper Locking Hydraulic Actuator Procedure 1, or Proce- dure 2, or Procedure 3, or Pro- cedure 4, or Procedure 5 result is unsatisfactory. (a) -Within 10 Days.(OPTION 1) (ACTION 2): Replace affected upper locking hydraulic actuator with a serviceable Upper Locking Hydraulic Actuator. -At the times specified in Table 6. (OPTION 1) (ACTION 3): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 6. -Before Further Flight.(OPTION 2) (ACTION 1): Replace affected upper locking hydraulic actuator with a serviceable Upper Locking Hydraulic Actuator. -At the times specified in Table 6. (OPTION 2) (ACTION 2): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 6. (a) Table 2, Table 4, Table 5, Table 6 refer to this table depending upon the condition(s) and action(s) as necessary. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 16 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 17 Table 4: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Spring Replacement Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.(OPTION 1) (ACTION 1): Deacti- vate the thrust reverser for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 3 result is unsatisfactory. -Within 10 Days.(OPTION 1) (ACTION 2) Replace affected torsion spring with a new torsion spring. (a) -Before Further Flight.(OPTION 2): Replace affected tor- sion spring with a new torsion spring. (a) -Before Further Flight.(OPTION 3) (ACTION 1): Deacti- vate the thrust reverser for flight. -At the times specified in Table 3. (OPTION 3) (ACTION 2): Do Upper Locking Hydraulic Actuator Replace- ment specified in Table 3. -At the times specified in Table 3. (OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 3. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 17 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 18 Table 5: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.(OPTION 1) (ACTION 1): Deacti- vate the thrust reverser for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 4 or Proce- dure 5 result is unsatisfactory. -Within 10 Days.(OPTION 1) (ACTION 2) Replace affected proximity sensor target with a new proximity sensor target. (a) -Before Further Flight.(OPTION 2): Replace affected proximity sensor target with a new proximity sensor target. (a) -Before Further Flight.(OPTION 3) (ACTION 1): Deacti- vate the thrust reverser for flight. -At the times specified in Table 3. (OPTION 3) (ACTION 2): Do Upper Locking Hydraulic Actuator Replace- ment specified in Table 3. -At the times specified in Table 3. (OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 3. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Table 6: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Proce- dures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.Do Procedure 1. (a)(b)All Airplanes that have replaced an Upper Locking Hydraulic Ac- tuator with a serviceable Upper Locking Hydraulic Actuator. Do Procedure 2. (a)(b) Do Procedure 3. (a)(b) Do Procedure 4. (a)(b) Do Procedure 5. (a)(b) --No further action is required.CONDITION 5: AFFECTED UPPER LOCKING HYDRAULIC ACTUATOR(S) PROCEDURE 1, PROCEDURE 2, PROCE- DURE 3, PROCEDURE 4, AND PROCEDURE 5 RESULTS ARE SATISFACTORY. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 18 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 19 Table 6: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Proce- dures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -At the times specified in Table 3. Do Upper Locking Hydraulic Actua- tor Replacement specified in Table 3. CONDITION 6: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. -At the times specified in Table 4. Do Upper Locking Hydraulic Actua- tor Spring Replacement or Upper Locking Hydraulic Actuator Replace- ment specified in Table 4. CONDITION 7: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. -At the times specified in Table 5. Do Upper Locking Hydraulic Actua- tor Proximity Sensor Target Re- placement or Upper Locking Hy- draulic Actuator Replacement specified in Table 5. CONDITION 8: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Table 7: Engine 2 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Whichever occurs later:Do Procedure 1. (a)(b)All Airplanes 1. Within 24 months af- ter the original issue date of Requirements Bulletin 737-78A1099 RB. Do Procedure 2. (a)(b) Do Procedure 3. (a)(b) Do Procedure 4. (a)(b) Do Procedure 5. (a)(b) 2. Within 24 months af- ter the date of issuance of the original standard certificate of airworthi- ness or the original ex- port certificate of airwor- thiness. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 19 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 20 Table 7: Engine 2 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition --No further action is required.CONDITION 9: LEFT AND RIGHT UPPER LOCKING HY- DRAULIC ACTUATORS' PRO- CEDURE 1, PROCEDURE 2, PROCEDURE 3, PROCEDURE 4, AND PROCEDURE 5 RE- SULTS ARE SATISFACTORY. -At the times specified in Table 8. Do Upper Locking Hydraulic Actua- tor Replacement specified in Table 8. CONDITION 10: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. -At the times specified in Table 9. Do Upper Locking Hydraulic Actua- tor Spring Replacement or Upper Locking Hydraulic Actuator Replace- ment specified in Table 9. CONDITION 11: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. -At the times specified in Table 10. Do Upper Locking Hydraulic Actua- tor Proximity Sensor Target Re- placement or Upper Locking Hy- draulic Actuator Replacement specified in Table 10. CONDITION 12: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 20 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 21 Table 8: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Replacement Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.(OPTION 1) (ACTION 1): Deacti- vate the thrust reverser for flight. Any Upper Locking Hydraulic Actuator Procedure 1, or Proce- dure 2, or Procedure 3, or Pro- cedure 4, or Procedure 5 result is unsatisfactory. (a) -Within 10 Days.(OPTION 1) (ACTION 2): Replace affected upper locking hydraulic actuator with a serviceable Upper Locking Hydraulic Actuator. -At the times specified in Table 11. (OPTION 1) (ACTION 3): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 11. -Before Further Flight.(OPTION 2) (ACTION 1): Replace affected upper locking hydraulic actuator with a serviceable Upper Locking Hydraulic Actuator. -At the times specified in Table 11. (OPTION 2) (ACTION 2): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 11. (a) Table 7, Table 9, Table 10, or Table 11 may refer to this table depending upon the condition(s) and action(s) as necessary. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 21 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 22 Table 9: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Spring Replacement Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.(OPTION 1) (ACTION 1): Deacti- vate the thrust reverser for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 3 result is unsatisfactory. -Within 10 Days.(OPTION 1) (ACTION 2) Replace affected torsion spring with a new torsion spring. (a) -Before Further Flight.(OPTION 2): Replace affected tor- sion spring with a new torsion spring. (a) -Before Further Flight.(OPTION 3) (ACTION 1): Deacti- vate the thrust reverser for flight. -At the times specified in Table 8. (OPTION 3) (ACTION 2) : Do Up- per Locking Hydraulic Actuator Re- placement specified in Table 8. -At the times specified in Table 8. (OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 8. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 22 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 23 Table 10: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.(OPTION 1) (ACTION 1): Deacti- vate the thrust reverser for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 4 or Proce- dure 5 result is unsatisfactory.. -Within 10 Days.(OPTION 1) (ACTION 2) Replace affected proximity sensor target with a new proximity sensor target. (a) -Before Further Flight.(OPTION 2): Replace affected proximity sensor target with a new proximity sensor target. (a) -Before Further Flight.(OPTION 3) (ACTION 1): Deacti- vate the thrust reverser for flight. -At the times specified in Table 8. (OPTION 3) (ACTION 2) : Do Up- per Locking Hydraulic Actuator Re- placement specified in Table 8. -At the times specified in Table 8. (OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 8. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Table 11: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Pro- cedures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before Further Flight.Do Procedure 1. (a)(b)All Airplanes that have replaced an Upper Locking Hydraulic Ac- tuator with a serviceable Upper Locking Hydraulic Actuator. Do Procedure 2. (a)(b) Do Procedure 3. (a)(b) Do Procedure 4. (a)(b) Do Procedure 5. (a)(b) --No further action is required.CONDITION 13: AFFECTED UPPER LOCKING HYDRAULIC ACTUATOR(S) PROCEDURE 1, PROCEDURE 2, PROCE- DURE 3, PROCEDURE 4, AND PROCEDURE 5 RESULTS ARE SATISFACTORY. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 23 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 24 Table 11: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Pro- cedures Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -At the times specified in Table 8. Do Upper Locking Hydraulic Actua- tor Replacement specified in Table 8. CONDITION 14: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. -At the times specified in Table 9. Do Upper Locking Hydraulic Actua- tor Spring Replacement or Upper Locking Hydraulic Actuator Replace- ment specified in Table 9. CONDITION 15: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. -At the times specified in Table 10. Do Upper Locking Hydraulic Actua- tor Proximity Sensor Target Re- placement or Upper Locking Hy- draulic Actuator Replacement specified in Table 10. CONDITION 16: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Table 12: All Airplanes - CMR Incorporation into Maintenance Program Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition -Before further flight after accomplishing any proce- dure specified in Table 1. (a) Incorporate 737- 600/700/700C/800/900/900ER CERTIFICA- TION MAINTENANCE REQUIREMENTS (CMR) document D626A001-9-03, dated September 2023, CMR item numbers 70- CMR-01, 78-CMR-01, 78-CMR-02, 78- CMR-03, 78-CMR-04, 78-CMR-05, 78- CMR-06, and 78-CMR-07 into the operators' maintenance program. (b) All Airplanes (a) Boeing recommends operators accomplish the initial inspection required by 78-CMR-07 prior to completing this RB on airplanes with more than 28,000 flight hours. The initial compliance time for accomplishing 78- CMR-07 is prior to the accumulation of 28,000 total flight hours. Failure to do so could result in the airplane being out of compliance until 78-CMR-07 is accomplished. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 24 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 25 Table 12: All Airplanes - CMR Incorporation into Maintenance Program Repeat Inter- val (Not to Ex- ceed) Boeing Recommended Compliance Time ActionCondition (b) Incorporating any CMR document D626A001-9-03, dated after September 2023, that contains the infor- mation specified in CMR item number 70-CMR-01, 78-CMR-01, 78-CMR-02, 78-CMR-03, 78-CMR-04, 78-CMR-05, 78-CMR-06, and 78-CMR-07 of CMR document D626A001-9-03, dated September 2023, is acceptable for compliance. 4. APPROVAL This Requirements Bulletin was examined by the Federal Aviation Administration (FAA). The changes specified in this document comply with the applicable regulations and are FAA approved, as well as European Union Aviation Safety Agency (EASA) approved for all EASA approved airplanes listed in the Requirements Bulletin effectivity. This document and its approval were based on the airplane in its original Boeing delivery configuration or as modified by other Boeing changes. If an airplane has a non-Boeing modification or repair that affects a component or system also affected by this Requirements Bulletin, the operator is responsible for obtaining appropriate regulatory agency approval before incorporating this Requirements Bulletin. In addition, the Manager of the FAA Continued Operational Safety Branch approves accomplishment of the inspections and applicable on-condition corrective actions defined in this Requirements Bulletin as an alternative method of compliance to the requirement of paragraph (i), (j), and (k) of AD 2019-18-03. All provisions of AD 2019-18-03 that are not specifically referenced in the above statement remain fully applicable and must be complied with accordingly. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 25 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 26 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 26 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT BLANK PAGE ### Page 27 5. ACCOMPLISHMENT INSTRUCTIONS A. GENERAL INFORMATION NOTE: 1. This is an Enhanced Required for Compliance document. There will be a separate Service Bulletin (SB) and a separate Requirements Bulletin (RB). If an RB is mandated by an Airworthiness Directive (AD), then all applicable requirements specified in the RB must be done. In the RB, the "Refer to the listed procedures..." column of the table(s) in the Work Instructions is for reference only. The procedures in that column are not required by the AD and are for guidance only. For the related SB, some locations are marked RC Start and RC End to identify the requirements that are restated from the RB. For the related SB, the areas between RC Start and RC End, including sub-steps and any figures identified between RC Start and RC End, must be done to comply with the AD. Therefore, an Alternative Method of Compliance (AMOC) is required for any deviations to steps between RC Start and RC End, including substeps and identified figures. For the related SB, the steps not between RC Start and RC End may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC; this is provided that the steps between RC Start and RC End, including sub-steps and identified figures, can still be done as specified, and the airplane can be put back in an airworthy condition. Figures not required for compliance are omitted from the RB. 2. This is an Enhanced Required for Compliance document. The Boeing processes used to create the Service Bulletin (SB) and the Requirements Bulletin (RB) ensure that the information between "RC Start" and "RC End" in the SB are identical to the information in the same sections (Compliance, Work Instructions...) of the RB which the SB refers to as the related document. 3. The compliance times for the actions in WORK INSTRUCTIONS are in Compliance. 4. These work instructions refer to procedures included in other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. 5. If it is necessary to remove more parts for access, you can remove those parts. If you can get access without removing identified parts, it is not necessary to remove all of the identified parts. Jacking and shoring limitations must be observed. 6. When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When more than one ACTION is given for a CONDITION or an OPTION, do all of the ACTION numbers for that CONDITION or OPTION. 7. Unless shown differently, these dimensions and tolerances are used: – Linear dimensions are in inches – Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch – Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch – Angular tolerance is plus or minus 2 degrees Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 27 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 28 – Hole dimensions for standard solid rivets and fasteners are in Structural Repair Manual (SRM) Chapter 51 – Torque Values: — Values for engine maintenance tasks are included in Chapter 70 of 737-600/700/800/900 Aircraft Maintenance Manual (AMM). — Non-standard torque values for maintenance tasks are included in the applicable installation step. 8. Use of colors in Figures is based on guidance from the ATA e-Business Program (ATA) iSpec 2200. 9. A serviceable Upper Locking Hydraulic Actuator is an actuator that has been evaluated in accordance with FAA-approved or accepted data and has been determined to be eligible for installation on type-certified products. B. WORK INSTRUCTIONS Actions Required for Compliance 1. Requirements: Table 1: Upper Locking Hydraulic Actuator Procedure Description and Satisfactory Procedure Result Definition Procedure Result - Satisfactory Defi- nition DescriptionProcedure Number Thrust Reverser Upper Locking Hy- draulic Actuator Manual Unlock Handle Assembly angular free-play is less than or equal to 9.40 degrees. Measurement of the Upper Locking Hy- draulic Actuator Manual Unlock Handle Assembly angular free-play. Procedure 1 (a) Thrust Reverser Sleeve stays in the fully stowed position as specified in Appendix A. Test of the integrity of the Upper Locking Hydraulic Actuator to find if the Thrust Reverser Sleeve stays in the fully stowed position. Procedure 2 Thrust Reverser Upper Locking Hy- draulic Actuator Manual Unlock Handle Assembly returns to its initial position. Operational check of the Upper Locking Hydraulic Actuator Manual Unlock Han- dle Assembly Torsion Spring. Procedure 3 (a) Thrust Reverser Upper Locking Hy- draulic Actuator distance between the center of the Proximity Sensor and Proximity Sensor Target Leading Edge is within 0.33 and 0.37 inches, inclusive- ly. Measurement of the clearance between the Upper Locking Hydraulic Actuator Proximity Sensor and Proximity Sensor Target Leading Edge. Procedure 4 Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 28 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 29 Table 1: Upper Locking Hydraulic Actuator Procedure Description and Satisfactory Procedure Result Definition Procedure Result - Satisfactory Defi- nition DescriptionProcedure Number – Upper Locking Hydraulic Actuator (Part Number (P/N) 315A2801-1) Proximity Sensor Target dimension 'A' and dimension 'B' is within 1.089 and 1.111 inches, inclusively. – Upper Locking Hydraulic Actuator (P/N 315A2801-4 or P/N 315A2801- 5) Proximity Sensor Target dimen- sion 'A' is within 0.949 and 0.971 inches, inclusively and dimension 'B' is within 0.789 and 0.811 inches, inclusively. Measurement of the Upper Locking Hy- draulic Actuator Proximity Sensor Tar- get. Procedure 5 (a) (a) This Procedure may be done off wing. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 29 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 30 Table 2: Engine 1 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 1: Open Access.-All Airplanes PART 2: Tool Usage for Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Angular Free-Play Measurement (Related to Procedure 1). -Do Procedure 1. (a)(b) -FIGURE 1 (P/N 315A2801-1) FIGURE 2 (P/N 315A2801-4 and 315A2801-5) PART 3: Work for Upper Locking Hydraulic Actuator Integrity Test (Related to Procedure 2) -Do Procedure 2. (a)(b) -APPENDIX A PART 4: Preparation for Upper Locking Hydraulic Actuator Manual Unlock Handle Torsion Spring Op- erational Check (Related to Procedure 3). -Do Procedure 3. (a)(b) -FIGURE 3 PART 6: Tool Usage for Upper Locking Hydraulic Actuator Proximity Sensor and Proximity Sensor Tar- get Clearance Measure- ment (Related to Procedure 4). -Do Procedure 4. (a)(b) -FIGURE 4 (P/N 315A2801-1) FIGURE 5 (P/N 315A2801-4 and 315A2801-5) -Do Procedure 5. (a)(b) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 30 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 31 Table 2: Engine 1 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 7: Work for Upper Locking Hydraulic Actuator Proximity Sensor Target Measurement (Related to Procedure 5). -FIGURE 6 (P/N 315A2801-1) FIGURE 7 (P/N 315A2801-4 and 315A2801-5) PART 10: Close Access.-No further action is required.CONDITION 1: LEFT AND RIGHT UPPER LOCKING HY- DRAULIC ACTUATORS' PRO- CEDURE 1, PROCEDURE 2, PROCEDURE 3, PROCEDURE 4, AND PROCEDURE 5 RE- SULTS ARE SATISFACTORY. --Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 3. CONDITION 2: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Spring Replace- ment or Upper Locking Hy- draulic Actuator Replace- ment specified in Table 4. CONDITION 3: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement or Up- per Locking Hydraulic Actua- tor Replacement specified in Table 5. CONDITION 4: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 31 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 32 Table 3: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Replacement Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 11: Thrust Reverser Inoperative -(OPTION 1) (ACTION 1): Deactivate the thrust revers- er for flight. Any Upper Locking Hydraulic Actuator Procedure 1, or Proce- dure 2, or Procedure 3, or Pro- cedure 4, or Procedure 5 result is unsatisfactory. (a) PART 10: Close Access.- PART 1: Open Access.-(OPTION 1) (ACTION 2): Replace affected upper locking hydraulic actuator with a serviceable Upper Locking Hydraulic Actuator. PART 9: Upper Locking Hydraulic Actuator Replace- ment. - --(OPTION 1) (ACTION 3): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 6. PART 9: Upper Locking Hydraulic Actuator Replace- ment. -(OPTION 2) (ACTION 1): Replace affected upper locking hydraulic actuator with a serviceable Upper Locking Hydraulic Actuator. --(OPTION 2) (ACTION 2): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 6. (a) Table 2, Table 4, Table 5, Table 6 refer to this table depending upon the condition(s) and action(s) as necessary. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 32 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 33 Table 4: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Spring Replacement Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 11: Thrust Reverser Inoperative -(OPTION 1) (ACTION 1): Deactivate the thrust revers- er for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 3 result is unsatisfactory. PART 10: Close Access.- PART 1: Open Access.-(OPTION 1) (ACTION 2) Replace affected torsion spring with a new torsion spring. PART 5: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Torsion Spring Replace- ment. - PART 5: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Torsion Spring Replace- ment. -(OPTION 2): Replace affect- ed torsion spring with a new torsion spring. (a) PART 11: Thrust Reverser Inoperative -(OPTION 3) (ACTION 1): Deactivate the thrust revers- er for flight. --(OPTION 3) (ACTION 2): Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 3. --(OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 3. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 33 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 34 Table 5: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 11: Thrust Reverser Inoperative -(OPTION 1) (ACTION 1): Deactivate the thrust revers- er for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 4 or Proce- dure 5 result is unsatisfactory. PART 10: Close Access.- PART 1: Open Access.-(OPTION 1) (ACTION 2) Replace affected proximity sensor target with a new proximity sensor target. PART 8: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Proximity Sensor Target Replacement. - PART 8: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Proximity Sensor Target Replacement. -(OPTION 2): Replace affect- ed proximity sensor target with a new proximity sensor target. (a) PART 11: Thrust Reverser Inoperative -(OPTION 3) (ACTION 1): Deactivate the thrust revers- er for flight. --(OPTION 3) (ACTION 2): Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 3. --(OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 3. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 34 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 35 Table 6: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Proce- dures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 1: Open Access.-All Airplanes that have replaced an Upper Locking Hydraulic Actuator with a serviceable Up- per Locking Hydraulic Actuator. PART 2: Tool Usage for Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Angular Free-Play Measurement (Related to Procedure 1). -Do Procedure 1. (a)(b) -FIGURE 1 (P/N 315A2801-1) FIGURE 2 (P/N 315A2801-4 and 315A2801-5) PART 3: Work for Upper Locking Hydraulic Actuator Integrity Test (Related to Procedure 2) -Do Procedure 2. (a)(b) -APPENDIX A PART 4: Preparation for Upper Locking Hydraulic Actuator Manual Unlock Handle Torsion Spring Op- erational Check (Related to Procedure 3). -Do Procedure 3. (a)(b) -FIGURE 3 PART 6: Tool Usage for Upper Locking Hydraulic Actuator Proximity Sensor and Proximity Sensor Tar- get Clearance Measure- ment (Related to Procedure 4). -Do Procedure 4. (a)(b) -FIGURE 4 (P/N 315A2801-1) FIGURE 5 (P/N 315A2801-4 and 315A2801-5) -Do Procedure 5. (a)(b) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 35 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 36 Table 6: Engine 1 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Proce- dures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 7: Work for Upper Locking Hydraulic Actuator Proximity Sensor Target Measurement (Related to Procedure 5). -FIGURE 6 (P/N 315A2801-1) FIGURE 7 (P/N 315A2801-4 and 315A2801-5) PART 10: Close Access.-No further action is required.CONDITION 5: AFFECTED UPPER LOCKING HYDRAULIC ACTUATOR(S) PROCEDURE 1, PROCEDURE 2, PROCE- DURE 3, PROCEDURE 4, AND PROCEDURE 5 RESULTS ARE SATISFACTORY. --Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 3. CONDITION 6: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Spring Replace- ment or Upper Locking Hy- draulic Actuator Replace- ment specified in Table 4. CONDITION 7: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement or Up- per Locking Hydraulic Actua- tor Replacement specified in Table 5. CONDITION 8: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 36 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 37 Table 7: Engine 2 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 1: Open Access.--All Airplanes PART 2: Tool Usage for Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Angular Free-Play Measurement (Related to Procedure 1). -Do Procedure 1. (a)(b) -FIGURE 1 (P/N 315A2801-1) FIGURE 2 (P/N 315A2801-4 and 315A2801-5) PART 3: Work for Upper Locking Hydraulic Actuator Integrity Test (Related to Procedure 2) -Do Procedure 2. (a)(b) -APPENDIX A PART 4: Preparation for Upper Locking Hydraulic Actuator Manual Unlock Handle Torsion Spring Op- erational Check (Related to Procedure 3). -Do Procedure 3. (a)(b) -FIGURE 3 PART 6: Tool Usage for Upper Locking Hydraulic Actuator Proximity Sensor and Proximity Sensor Tar- get Clearance Measure- ment (Related to Procedure 4). -Do Procedure 4. (a)(b) -FIGURE 4 (P/N 315A2801-1) FIGURE 5 (P/N 315A2801-4 and 315A2801-5) -Do Procedure 5. (a)(b) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 37 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 38 Table 7: Engine 2 - Left and Right Thrust Reverser Half - Upper Locking Hydraulic Actuator Procedures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 7: Work for Upper Locking Hydraulic Actuator Proximity Sensor Target Measurement (Related to Procedure 5). -FIGURE 6 (P/N 315A2801-1) FIGURE 7 (P/N 315A2801-4 and 315A2801-5) PART 10: Close Access.-No further action is required.CONDITION 9: LEFT AND RIGHT UPPER LOCKING HY- DRAULIC ACTUATORS' PRO- CEDURE 1, PROCEDURE 2, PROCEDURE 3, PROCEDURE 4, AND PROCEDURE 5 RE- SULTS ARE SATISFACTORY. --Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 8. CONDITION 10: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Spring Replace- ment or Upper Locking Hy- draulic Actuator Replace- ment specified in Table 9. CONDITION 11: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement or Up- per Locking Hydraulic Actua- tor Replacement specified in Table 10. CONDITION 12: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 38 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 39 Table 8: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Replacement Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 11: Thrust Reverser Inoperative. -(OPTION 1) (ACTION 1): Deactivate the thrust revers- er for flight. Any Upper Locking Hydraulic Actuator Procedure 1, or Proce- dure 2, or Procedure 3, or Pro- cedure 4, or Procedure 5 result is unsatisfactory. (a) PART 10: Close Access.- PART 1: Open Access.-(OPTION 1) (ACTION 2): Replace affected upper locking hydraulic actuator with serviceable Upper Locking Hydraulic Actuator. PART 9: Upper Locking Hydraulic Actuator Replace- ment. - --(OPTION 1) (ACTION 3): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 11. PART 9: Upper Locking Hydraulic Actuator Replace- ment. -(OPTION 2) (ACTION 1): Replace affected upper locking hydraulic actuator with serviceable Upper Locking Hydraulic Actuator. --(OPTION 2) (ACTION 2): Do Upper Locking Hydraulic Actuator Post Replacement Procedure specified in Table 11. (a) Table 7, Table 9, Table 10, or Table 11 may refer to this table depending upon the condition(s) and action(s) as necessary. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 39 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 40 Table 9: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Spring Replacement Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 11: Thrust Reverser Inoperative. -(OPTION 1) (ACTION 1): Deactivate the thrust revers- er for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 3 result is unsatisfactory. PART 10: Close Access.- PART 1: Open Access.-(OPTION 1) (ACTION 2) Replace affected torsion spring with a new torsion spring. PART 5: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Torsion Spring Replace- ment. - PART 5: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Torsion Spring Replace- ment. -(OPTION 2): Replace affect- ed torsion spring with a new torsion spring. (a) PART 11: Thrust Reverser Inoperative. -(OPTION 3) (ACTION 1): Deactivate the thrust revers- er for flight. --(OPTION 3) (ACTION 2): Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 8. --(OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 8. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 40 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 41 Table 10: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 11: Thrust Reverser Inoperative -(OPTION 1) (ACTION 1): Deactivate the thrust revers- er for flight. (a) Any Upper Locking Hydraulic Actuator Procedure 4 or Proce- dure 5 result is unsatisfactory. PART 10: Close Access.- PART 1: Open Access.-(OPTION 1) (ACTION 2) Replace affected proximity sensor target with a new proximity sensor target. PART 8: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Proximity Sensor Target Replacement. - PART 8: Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Proximity Sensor Target Replacement. -(OPTION 2): Replace affect- ed proximity sensor target with a new proximity sensor target. (a) PART 11: Thrust Reverser Inoperative -(OPTION 3) (ACTION 1): Deactivate the thrust revers- er for flight. --(OPTION 3) (ACTION 2): Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 8. --(OPTION 4): Do Upper Locking Hydraulic Actuator Replacement specified in Table 8. (a) You cannot do this OPTION unless the results of Procedure 1 and Procedure 2 for the affected Thrust Reverser Upper Locking Hydraulic Actuator are satisfactory. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 41 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 42 Table 11: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Pro- cedures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 1: Open Access.-All Airplanes that have replaced an Upper Locking Hydraulic Actuator with a serviceable Up- per Locking Hydraulic Actuator. PART 2: Tool Usage for Upper Locking Hydraulic Actuator Manual Unlock Handle Assembly Angular Free-Play Measurement (Related to Procedure 1). -Do Procedure 1. (a)(b) -FIGURE 1 (P/N 315A2801-1) FIGURE 2 (P/N 315A2801-4 and 315A2801-5) PART 3: Work for Upper Locking Hydraulic Actuator Integrity Test (Related to Procedure 2) -Do Procedure 2. (a)(b) -APPENDIX A PART 4: Preparation for Upper Locking Hydraulic Actuator Manual Unlock Handle Torsion Spring Op- erational Check (Related to Procedure 3). -Do Procedure 3. (a)(b) -FIGURE 3 PART 6: Tool Usage for Upper Locking Hydraulic Actuator Proximity Sensor and Proximity Sensor Tar- get Clearance Measure- ment (Related to Procedure 4). -Do Procedure 4. (a)(b) -FIGURE 4 (P/N 315A2801-1) FIGURE 5 (P/N 315A2801-4 and 315A2801-5) -Do Procedure 5. (a)(b) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 42 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 43 Table 11: Engine 2 - Thrust Reverser Half - Upper Locking Hydraulic Actuator - Post Replacement Pro- cedures Refer to the listed proce- dures in SB 737-78A1099 Original Issue or later ap- proved revisions as an accepted procedure Method of Compli- ance ActionCondition PART 7: Work for Upper Locking Hydraulic Actuator Proximity Sensor Target Measurement (Related to Procedure 5). -FIGURE 6 (P/N 315A2801-1) FIGURE 7 (P/N 315A2801-4 and 315A2801-5) PART 10: Close Access.-No further action is required.CONDITION 13: AFFECTED UPPER LOCKING HYDRAULIC ACTUATOR(S) PROCEDURE 1, PROCEDURE 2, PROCE- DURE 3, PROCEDURE 4, AND PROCEDURE 5 RESULTS ARE SATISFACTORY. --Do Upper Locking Hydraulic Actuator Replacement spec- ified in Table 8. CONDITION 14: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 1 OR PROCEDURE 2 RESULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Spring Replace- ment or Upper Locking Hy- draulic Actuator Replace- ment specified in Table 9. CONDITION 15: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 3 RE- SULT IS UNSATISFACTORY. --Do Upper Locking Hydraulic Actuator Proximity Sensor Target Replacement or Up- per Locking Hydraulic Actua- tor Replacement specified in Table 10. CONDITION 16: ANY UPPER LOCKING HYDRAULIC ACTU- ATOR PROCEDURE 4 OR PROCEDURE 5 RESULT IS UNSATISFACTORY. (a) When any procedure listed in this table (i.e., procedures 1 thru 5) is started, all the procedures must be done before further flight, except as specified in flagnote (b) of this table. The procedures may be done in any order except as specified in flagnote (a) of Tables 4, 5, 9, and 10. (b) It is not required to do remaining procedures if, during accomplishment of any procedure, the result is unsatisfactory and all applicable on-condition actions are done. This is because once unsatisfactory con- ditions for that procedure are resolved, the intent of satisfactory completion of that procedure would be met. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 43 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 44 Table 12: All Airplanes - CMR Incorporation into Maintenance Program Refer to the listed procedures in SB 737- 78A1099 Original Is- sue or later approved revisions as an ac- cepted procedure Method of Compliance ActionCondition --Incorporate 737- 600/700/700C/800/900/900ER CERTIFICA- TION MAINTENANCE REQUIREMENTS (CMR) document D626A001-9-03, dated September 2023, CMR item numbers 70- CMR-01, 78-CMR-01, 78-CMR-02, 78- CMR-03, 78-CMR-04, 78-CMR-05, 78- CMR-06, and 78-CMR-07 into the operators' maintenance program. (a) All Airplanes (a) Incorporating any CMR document D626A001-9-03, dated after September 2023, that contains the infor- mation specified in CMR item number 70-CMR-01, 78-CMR-01, 78-CMR-02, 78-CMR-03, 78-CMR-04, 78-CMR-05, 78-CMR-06, and 78-CMR-07 of CMR document D626A001-9-03, dated September 2023, is acceptable for compliance. Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 44 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 45 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT UPPER LOCKING HYDRAULIC ACTUATOR 2921506 FIGURE 1: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) MANUAL UNLOCK HANDLE ASSEMBLY ANGULAR FREE-PLAY MEASUREMENT (RELATED TO PROCEDURE 1) (SHEET 1 OF 2) Original Issue: July 08, 2025 737-78A1099 RB Export Controlled ECCN: 9E991 See page 1 for details 45 of 70 ### Page 46 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each upper locking hydraulic actuator. More DataQtyIdentificationNameTaskStep (a)(b)(c)--ANGULAR FREE- PLAY Measure1 (a) Measure the angle from the forward vertical edge of the manual unlock handle assembly. (b) Measurement may be done off wing. (c) C78042-23 (OR C78042-17) may be used as an aid for the angular free-play measurement. FIGURE 1: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) MANUAL UNLOCK HANDLE ASSEMBLY ANGULAR FREE-PLAY MEASUREMENT (RELATED TO PROCEDURE 1) (SHEET 2 OF 2) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 46 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 47 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT ... UPPER LOCKING HYDRAULIC ACTUATOR 2910222 FIGURE 2: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) MANUAL UNLOCK HANDLE ASSEMBLY ANGULAR FREE-PLAY MEASUREMENT (RELATED TO PROCEDURE 1) (SHEET 1 OF 2) Original Issue: July 08, 2025 737-78A1099 RB Export Controlled ECCN: 9E991 See page 1 for details 47 of 70 ### Page 48 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each upper locking hydraulic actuator. More DataQtyIdentificationNameTaskStep (a)(b)--ANGULAR FREE- PLAY Measure1 (a) Measurement may be done off wing. (b) C78042-23 (OR C78042-17) may be used as an aid for the angular free-play measurement. FIGURE 2: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) MANUAL UNLOCK HANDLE ASSEMBLY ANGULAR FREE-PLAY MEASUREMENT (RELATED TO PROCEDURE 1) (SHEET 2 OF 2) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 48 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 49 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT UPPER LOCKING HYDRAULIC ACTUATOR TYPICAL 2910244 FIGURE 3: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR MANUAL UNLOCK HANDLE ASSEMBLY TORSION SPRING OPERATIONAL CHECK (RELATED TO PROCEDURE 3) (SHEET 1 OF 2) Original Issue: July 08, 2025 737-78A1099 RB Export Controlled ECCN: 9E991 See page 1 for details 49 of 70 ### Page 50 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each upper locking hydraulic actuator. More DataQtyIdentificationNameTaskStep (a)(b)1315A2857-1 OR 315A2857-3 MANUAL UNLOCK HANDLE ASSEMBLY Move1 (a) Move the manual unlock handle assembly in an aft direction until it stops. Do not unlock the handle. Let go of the manual unlock handle assembly to make sure it returns to its initial position. (b) Operational Check may be done off wing. FIGURE 3: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR MANUAL UNLOCK HANDLE ASSEMBLY TORSION SPRING OPERATIONAL CHECK (RELATED TO PROCEDURE 3) (SHEET 2 OF 2) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 50 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 51 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT UPPER LOCKING HYDRAULIC ACTUATOR 2922071 FIGURE 4: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) (SHEET 1 OF 3) Original Issue: July 08, 2025 737-78A1099 RB Export Controlled ECCN: 9E991 See page 1 for details 51 of 70 ### Page 52 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT PROXIMITY SENSOR CENTER PROXIMITY SENSOR TARGET LEADING EDGE MANUAL UNLOCK HANDLE ASSEMBLY (LOCKED POSITION) FWD PROXIMITY SENSOR NOT SHOWN 2922072 FIGURE 4: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) (SHEET 2 OF 3) Original Issue: July 08, 2025 Export Controlled ECCN: 9E991 737-78A1099 RB See page 1 for details 52 of 70 ### Page 53 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each upper locking hydraulic actuator. More DataQtyIdentificationNameTaskStep (a)(b)1-CLEARANCEMeasure1 (a) Measure the distance between the center of the proximity sensor and the leading edge of the proximity sensor target. (b) C78030-1 may be used as an aid for the clearance measurement. A correctly positioned target is where the "second step" of the Gap Measurement Gauge does not pass the leading edge of the target. Refer to the instruction placard supplied with the Gap Measurement Gauge. Refer to 737-600/700/800/900 AMM 78-34-03, Lock Sensor Target Adjustment, for the use of the Gap Measurement Gauge, C78030- 1, as an accepted procedure. FIGURE 4: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) (SHEET 3 OF 3) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 53 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 54 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT UPPER LOCKING HYDRAULIC ACTUATOR TYPICAL 2910271 FIGURE 5: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) (SHEET 1 OF 3) Original Issue: July 08, 2025 737-78A1099 RB Export Controlled ECCN: 9E991 See page 1 for details 54 of 70 ### Page 55 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT PROXIMITY SENSOR CENTER PROXIMITY SENSOR TARGET LEADING EDGE MANUAL UNLOCK HANDLE ASSEMBLY (LOCKED POSITION) FWD PROXIMITY SENSOR NOT SHOWN 2910273 FIGURE 5: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) (SHEET 2 OF 3) Original Issue: July 08, 2025 Export Controlled ECCN: 9E991 737-78A1099 RB See page 1 for details 55 of 70 ### Page 56 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each upper locking hydraulic actuator. More DataQtyIdentificationNameTaskStep (a)(b)1-CLEARANCEMeasure1 (a) Measure the distance between the center of the proximity sensor and the leading edge of the proximity sensor target. (b) C78030-1 may be used as an aid for the clearance measurement. A correctly positioned target is where the "second step" of the Gap Measurement Gauge does not pass the leading edge of the target. Refer to the instruction placard supplied with the Gap Measurement Gauge. Refer to 737-600/700/800/900 AMM 78-34-03, Lock Sensor Target Adjustment, for the use of the Gap Measurement Gauge, C78030- 1, as an accepted procedure. FIGURE 5: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) PROXIMITY SENSOR CENTER AND THE PROXIMITY SENSOR TARGET LEADING EDGE CLEARANCE MEASUREMENT (RELATED TO PROCEDURE 4) (SHEET 3 OF 3) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 56 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 57 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT UPPER LOCKING HYDRAULIC ACTUATOR 2922073 FIGURE 6: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR TARGET MEASUREMENT (RELATED TO PROCEDURE 5) (SHEET 1 OF 3) Original Issue: July 08, 2025 Export Controlled ECCN: 9E991 737-78A1099 RB See page 1 for details 57 of 70 ### Page 58 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT DIMENSION 'A' — DIMENSION'B' PROXIMITY SENSOR TARGET MANUAL UNLOCK HANDLE ASSEMBLY FWD PROXIMITY SENSOR NOT SHOWN 2922079 FIGURE 6: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR TARGET MEASUREMENT (RELATED TO PROCEDURE 5) (SHEET 2 OF 3) Original Issue: July 08, 2025 Export Controlled ECCN: 9E991 737-78A1099 RB See page 1 for details 58 of 70 ### Page 59 The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each upper hydraulic locking actuator. More DataQtyIdentificationNameTaskStep (a)2-DIMENSIONMeasure1 (a) C78042-30 may be used as an aid for target dimension measurements. FIGURE 6: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-1) PROXIMITY SENSOR TARGET MEASUREMENT (RELATED TO PROCEDURE 5) (SHEET 3 OF 3) Export Controlled ECCN: 9E991 See page 1 for details Original Issue: July 08, 2025 737-78A1099 RB 59 of 70 REQUIREMENTS BULLETIN 737-78A1099 ALERTALERT ### Page 60 (OCR) REQUIREMENTS BULLETIN 737-78A1099 ALERT ALERT UPPER LOCKING HYDRAULIC ACTUATOR TYPICAL 2910548 FIGURE 7: ENGINE - THRUST REVERSER HALF - UPPER LOCKING HYDRAULIC ACTUATOR (PART NUMBER 315A2801-4 OR 315A2801-5) PROXIMITY SENSOR TARGET MEASUREMENT (RELATED TO PROCEDURE 5) (SHEET 1 OF 3) Original Issue: July 08, 2025 737-78A1099 RB Export Controlled ECCN: 9E991 See page 1 for details 60 of 70 The text continues at https://openairdocs.org/service-documents/boeing/737-78a1099/file/a57cb4b51ad3.md?from=61 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. 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