AC 121-1A

Change 4Historical

Advisory circular · Standard Operations Specifications - Aircraft Maintenance Handbook

Approved
July 7, 1978
Last reviewed
October 25, 2024
Cancels
AC121-1A CHG 3AC120-21AC120-24A
Family
AC 121-1 · 1 version
Revision
A, change 4
14 CFR parts
1

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 190–201
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Zone 71 L/R 4E Lower Wing to Fuselage Fillet Sta. 680 to 980, Zone 72 L/R 4E Fuselage Less Zones 67 & 68, From Sta. 225 to 1485 Above Cusp., Zone 73 4E (62F) Internal Inspection of Main Cabin Cargo Door Jamb Intercostals and Frames at Fuselage Sta. 330 and 470, Zone 73 4E Left and Right Main Landing Gear and Wheel Well, Zone 74 L/R 4E Wheel Well Keel, Zone 74 L/R E Effective date ____________________ Page 10 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-62/62F

STRUCTURE INSPECTION PROGRAM Overhaul Inspection & Period Check Period Fuselage (Continued) Left and Right Horizontal Stabilizer Leading Edge, Zone 75 L/R 2E Forward Face of Stabilizer Front Spar, Zone 75 L/R E Left and Right Horizontal Stabilizer Outer Panel, Zone 76 L/R 4E Horizontal Stabilizer Center

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Section, Zone 77 2E Left and Right Elevator and Tabs, Zone 78 L/R E Vertical Stabilizer Leading Edge, Zone 79 2E Vertical Stabilizer Front Spar To Rear Spar, Zone 80 2E Vertical Stabilizer Tip, Zone 81 3E Rudder and Tab, Zone 82 2E Rudder Hinge Fitting and Damper E Horizontal Stabilizer Tip, Zone 83 L/R 2E Left and Right Aft Fillet, Zone 84, L/R 2E Effective date ____________________ ---------------------------------------------------------------- ---------------------------------------------------------------- FIGURE 29. OPERATIONS SPECIFICATIONS/AIRCRAFT MAINTENANCE

- DOUGLAS DC-8-63/63F Form Approved.

UNITED STATES OF AMERICA Budget Bureau FEDERAL AVIATION AGENCY No. 04-R075.

WASHINGTON PART D PAGE 1 of 10 PAGES

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F Following are additional items and/or changes to the original Douglas DC-8/F aircraft specification listing which apply to the Douglas DC-8-63/63F aircraft.

Zone diagrams for the Douglas DC-8/F are also applicable to

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Douglas DC-8-63/63F aircraft; however, fuselage stations listed will only apply to the Douglas DC-8/F.

Overhaul Inspection & Air Conditioning, Chapter 21 Period Check Period Valve, Fan Unloader OC D,E Filter, Recirculating Fan OC D Valve, Cold Air Bypass OC D,E Electrical Power, Chapter 24 Constant Speed Drive, 30 KVA 3,000 D-Oil Change Generator, 30 KVA 5,000 B,D-Oil Level Check Panel, Voltage Regulator and Generator Control OC E - F/C Cooler, Air/Oil CSD EO D Fire Protection, Chapter 26 (63F) Pyrotector (Smoke Detector) OC A,B,D,E Container - Fire Extinguisher * B,D,E Cartridge - Dual Squib 4 years B,D,E * Hydrostatic and life limits shall be entered here and shall not exceed those set forth in Part 173, Chapter I, Subtitle "B" of CFR Title 49.

Flight Controls, Chapter 27 Cylinder and Control Valve Rudder Power 2E D Fuel, Chapter 28 Pump, Residual Fuel Scavenge Center Wing OC D, F/C @ E Heater, Sump, Center Wing OC D, F/C @ E Valve, Fuel Scavenge Selector Center Wing OC D, F/C @ E Ice and Rain Protection, Chapter 30 Rain Repellent System OC A,B,D Tail De-icing Timer OC D,E Effective date ____________________ Page 2 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

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Overhaul Inspection & Landing Gear, Chapter 32 Period Check Period Bogie Beam, Main Landing Gear, Non-Swivel 12,500 D Energy Absorber, Tailskid O.C. A,B,D Valve, Nose Wheel Steering, Bypass 12,500 D Limiter, Brake Fluid Quantity 12,500 D Pneumatic System, Chapter 36 Heat Exchanger, Bleed Air O.C. D - E.C.

Valve, Bleed Air Temperature Control O.C. D - F/C @ E Valve, 16th Stage Shut-off O.C. D - F/C @ E.O.

Valve, 12th Stage Check O.C. D - F/C @ E.O.

Amplifier, Pneumatic Manifold Rupture Warning O.C. D,E Sensing Element, Pneumatic Manifold Rupture Warning O.C. E Doors, Chapter 52 (63F) Main Cabin Cargo Door Hydraulic System (Same as 55F) O.C. See NOTE * (63F) Cylinder Assembly, Main Cabin Cargo Door Actuating O.C. See NOTE * * NOTE: The design of the main cabin cargo door installation is such that in the normally latched and locked position, it can be structurally compared to any fixed portion of the fuselage.

It is only when the door is actuated open on the ground during cargo loading operations that the heaviest loads are incurred. These loads would be greatest at the upper door hinge and hydraulic actuating cylinder attach points. The door seal would also be subject to damage at this time.

Thus, door utilization established inspection frequency. Under these conditions, Douglas suggests the following procedure for purposes of inspection:

(1) Conduct a general visual area inspection of the upper cargo door hinge attachments, door jamb, door actuating cylinder attachments, door seal and latching mechanism at the scheduled "D" service following use of the aircraft in cargo configuration; (2) If the

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aircraft is operated solely in the Effective date ____________________ Page 3 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F Overhaul Inspection & Period Check Period * NOTE: (Continued) passenger configuration, conduct a general visual area inspection (as above) no later than "E" frequency.

Powerplant, Chapter 71 Nose Cowl and Fan Duct Attach.

Fireseal, Engine Mounts Engine Control & Accessory Brackets Change D Engine Air, Chapter 75 Valve, Engine Nose Cowl Anti-ice Shut-off O.C. D, F/C @ E.O.

Thrust Reverser, Chapter 78 Thrust Reverser Assembly O.C. B,D (X-Ray Reverser Structure on Aircraft @ E Frequency) Pump Assembly, Electric Driven 5000 D Accumulator 16,000 D Cylinder, Thrust Reverser Actuator 12,000 D Valve, Thrust Reverser Control 12,000 D Cylinder, Stow Latch, Thrust Reverser 12,000 D Filter Assembly O.C. E

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Effective date ____________________ Page 4 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

STRUCTURE INSPECTION PROGRAM E Check - 4000 Hours Overhaul Inspection & D Check - 500 Hours Period Check Period Wings Wing Tip, Zone 5 L/R 5E D Wing Outboard of Sta. Xw 408, Combined Zone 9 Zone 9 L/R & Zone 6 L/R 5E L/R & Zone 6 L/R Wing Leading Edge Sta. Xfs 710 to Xw 736 Cant, Zone 7 L/R E Wing Leading Edge Sta. Xw 485 to Xfs 710, Zone 8 L/R E * No. 1 & 4 Alternate Fuel Tanks, E-Sample Zone 9 L/R and Zone 6 L/R 5E One Tank Per Aircraft Wing Trailing Edge Sta. Xw 408 Aileron Hinge to Xw 736 Cant, Aft of Rear Brackets and Spar, Zone 10 L/R E Bolts 4D Aileron and Tab, Zone 11 L/R E Hinges & Attachments 4D Aileron Leading Edge Balance Weights 2E Wing Leading Edge at Outboard Pylon Sta. Xfs 526 to Xw 485, Zone 12 L/R E Outboard Pylon, Apron and Nacelle Access Doors, Zone 13 L/R E 2D * Pylon Upper Spar, and Pylon

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Leading Edge Attachments, Zone 13 L/R E 2D Effective date ____________________ Page 5 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

STRUCTURE INSPECTION PROGRAM Overhaul Inspection & Period Check Period Wings (Continued) * Pylon to Wing Front Spar and Pylon to Wing Attachments, Zone 13 L/R E 2D Inboard Pylon, Apron and Nacelle Access Doors, Zone 14 L/R E 2D * Pylon Upper Spar and Pylon Leading Edge Attachments, Zone 14 L/R E 2D * Pylon to Wing Front Spar and Pylon to Wing Attachments, Zone 14 L/R E 2D Wing Leading Edge Sta. Xw 408 to Xfs 526, Zone 15 L/R E Wing Leading Edge Sta. Xw 257 to Xw 408, Zone 16 L/R E * No. 1 & 4 Main Fuel Tanks, Zone 17 L/R 5E E-Sample One Tank Per Airplane Wing Trailing Edge from Outboard Auxiliary Spar to Sta. Xw 408, Zone 18 L/R E Main Landing Gear Support Fittings & Auxiliary Spars,

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Zone 19 L/R 2E Wing Leading Edge at Inboard Pylon Sta. Xfs 250 to Xw 257, Zone 20 L/R E Wing Leading Edge Sta. Xw0 to Xfs. 207, Zone 21 L/R & 22 L/R External Inspection E Wing Leading Edge Xfs Sta. 207 to Xs 250, Zone 20 & Zone 21 External Inspection E Wing Leading Edge Xfs Sta. 207 to Xs 250 Zone 20 & Zone 21 including Forward Face of Wing Front Spar, as visible. E Effective date ____________________ Page 6 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

STRUCTURE INSPECTION PROGRAM Overhaul Inspection & Period Check Period Wings (Continued) Leading Edge Fuel Tanks, Zone 21 L/R & Zone 22 L/R 5E No. 2 & 3 Main and Alternate Fuel Tanks, Zone 23 L/R & Zone 24 L/R 5E Outboard Wing Flap Interior Structure, Zone 25 L/R 3E Flap Hinge Support Fittings, Zone 25 L/R 2E Aft Side of Flap Spar, Zone 25 L/R 4E Inboard Wing Flap & Links at the

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Outboard End of the Flap, which Connect to the Inboard End of the Outboard Flap, Zone 26 L/R E Flap Hinge Support Fittings and Aft Side of Flap Spar, Zone 26 L/R 4E Interior or Center Wing Sta.

Xcw 0 to Xcw 69.5 (Front to Rear Spar), Zone 27 L/R 5E NOTE: * Specified times for items identified by (*) applicable to all operators until satisfactory service experience accumulated.

Fuselage (All stations are DC-8-63/63F, Identical to DC-8-61/61F) Radome, Zone 51 E Fuselage Turbo Compressor Compartment, Zone 52 4E Effective date ____________________ Page 7 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

STRUCTURE INSPECTION PROGRAM Overhaul Inspection & Period Check Period Fuselage (Continued) Navigation Antenna Compartment, Zone 53 4E Nose Gear Wheel Well, Zone 54 4E Nose Wheel Well Tunnel, Zone 55 L/R 4E Air Conditioning Accessory Compartment Sta. 8 to 70,

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Zone 56 E Forward Cargo Compartment Sta.

70 to 640, Zone 57 4E Forward Cargo Compartment Tunnel Sta. 70 to 640, Zone 57 L/R 4E Fuselage Accessory Compartment Sta. 640 to 680, Zone 58 E Upper and Lower Front Spar Cap, Forward Face of Front Spar Web Upper and Lower Front Spar Caps and Splice Plates at Sta.

Xcw 0, Zone 58 4E Aft Cargo Compartment Sta. 980 to 1540, Zone 59 4E Aft Cargo Compartment Tunnel, Sta. 980 to 1540, Zone 59 L/R 4E Fuselage Belly Compartment Sta.

1540 to Pressure Panel at Sta.

1766, Zone 60 E Aft Fuselage Sta. 1766 to 1890, Zone 61 E Effective date ____________________ Page 8 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

STRUCTURE INSPECTION PROGRAM Overhaul Inspection & Period Check Period Fuselage (Continued) Aft Face and Periphery of Pressure Panel at Fuselage Sta. 1766, Zone 61 E Fuselage Tail Cone, Zone 62 E

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Fuselage Sta. -131 to -117 above Cockpit Floor, Zone 63 4E Fuselage Cockpit Sta. -117 to -52, Zone 64 4E Fuselage Cockpit Sta. -52 to 25 above Floor, Zone 65 L/R E Fuselage Sta. 8 to -131 Between Cockpit Floor and Horizontal Pressure Panel, Zone 66 E Forward and Aft Galley Areas Sta. 360 to 460 & Sta. 1500 to 1620 R. Side, Zone 67 E Scuff Plates at Forward and Aft Service Door Jambs. Internal Inspection of Door Jambs.

Intercostals & Frames at Fuselage Sta. 395, 430, 1538 & 1575. Inspection of Door Hinge Attachments & Door Snubber Attachments to Jambs, Zone 67 4E Forward and Aft Lavatory Areas, Zone 68 4E Vertical Stabilizer Front & Center Spar Attachments to Fuselage Longerons, Between Fuselage Sta's. 1700 and 1766, Zone 68 4E Effective date ____________________ Page 9 of 10

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE DOUGLAS DC-8-63/63F

STRUCTURE INSPECTION PROGRAM Overhaul Inspection & Period Check Period

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Fuselage (Continued) Upper and Lower Attachments of Aft Pressure Panel Vertical Beam (Center Line-Forward Face of Pressure Panel) Fuselage Sta. 1766, Zone 68 4E Fuselage Entrance Doors, Zone 69 4E (63F) Main Cabin Cargo Door, Zone 69 4E Emergency Exit Doors, Type I and Type III, Zone 69 4E Fuselage Sta. 680 to 980 Between Bottom of Floor and Top of Wing and Wheel Well, Zone 70 4E Upper Wing to Fuselage Fillet, Zone 71 L/R 4E Lower Wing to Fuselage Fillet Sta. 680 to 980, Zone 72 L/R 4E Fuselage Less Zones 67 & 68, From Sta. 25 to 1645 above Cusp., Zone 73 4E (63F) Internal Inspection of Main Cabin Cargo Door Jamb Intercostals and Frames at Fuselage Sta. 130 to 270, Zone 73 4E Internal Inspection of Type I and Type III Emergency Exit Door Jambs, Intercostals and Frames 4E Left and Right Main Landing Gear and Wheel Well, Zone 74 L/R 4E Wheel Well Keel, Zone 74 L/R E Effective date ____________________