# AD 56-26-03: Crankshaft - Type: Airworthiness directive - Status: Historical - Products: Pratt & Whitney Division Military R-985 Series, Wasp Jr. A, Wasp Jr. B-4, Wasp Jr. B-5, Wasp Jr. SB, Wasp Jr. SB-2, Wasp Jr. SB-3, Wasp Jr. T1B, Wasp Jr. T1B2, Wasp Jr. T1B3, Wasp Jr. T3A, Wasp Jr. TB and 1 more - Published: April 11, 1957 - Issued: April 4, 1957 - Superseded by: Nothing supersedes this AD - Product type: Engine - Amendment: Unknown - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DRSDOCID105122107220240410153434.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/56-26-03 ## The airworthiness directive This is OCR from the scanned FAA AD. OCR can misread letters and numbers. 2422 RULES AND REGULATIONS holes ΒΌ of an inch from the existing center 56-26-4 VICKERS-ARMSTRONGS Applies (Hiller Service Information Letter No. 111 hole. In addition, all existing field stocks all Model Viscount Aircraft. covers this subject.) as well as the fuel tank caps on aircraft which have been replaced since September Service Compliance required as indicated. experience has indicated that 56-27-3 PIPER Serial No. 23-1 through 23-800 except 23- Applies to Model PA-23, 26, 1956 from stock procured from the Piper Service Department, must be reworked. (Piper Immediate Action Service Bulletin cracks may develop in certain pre-modifica- tion brackets. D. 1031 engine nacelle Accordingly. Vickers-Armstrongs attachment 769, 23-777, 23-784, 23-787, 23-794, 23-797 732, 23-736, 23-739, 23-740, 23-741, 23- No. 148 dated November 26, 1956, covers this same subject.) Wasp Jr. and Military R-985 series en- gines, except those used in helicopters. Registration Board considers the inspections recommended therein mandatory, in Leaflet No. 111, Issue 1, dated October 19, 1956, covering this subject. (aircraft) Ltd. issued Preliminary Technical When brackets to Mod. D. 90" angle, it will be necessary to remove both alleron balance weight bracket at a point where the bracket tubes are welded to form a In order to prevent fatigue cracking in the Compliance required by February 1, 1957. It has been determined that AD 54-22-2 Compliance required as indicated. 1031 are installed, the special inspections detailed in P. T. L. No. 111 do not apply. the right and left alleron balance weight brackets and reinforce them with gussets, was not effective in preventing crankshaft This supersedes A. D. Note 55-22-5. Piper Part No. 17126-07 in accordance with at the thrust nut threads the instructions and sketch failures of these crankshafts are still occurs loss of the propeller in flight as Applies to all Model CV- Piper Service Bulletin No. 149 dated De- shaft by the rework in "B" below has been Increased strength afforded the crank- Compliance required as noted below. - A report has been received concerning the 56-27-4 RYAN Applies to Navion B type air- determined to be necessary to raise the level of safety of these engines. cluded the smoothly blended thread roots This rework in- failure of the elevator servo tab rod on a version of the Model CV-340 aircraft. the tabs on the subject model aircraft are Service downdraft cooling kit installa- or Hackenberg Sales and Reading Aviation and a closely controlled undercut depth as required by AD 54-22-2 and the special in- unbalanced, a serious flutter condition re- sulted and a critical accident was narrowly Compliance required not later than July 1, spections and shot peening as required by In view of the fact that the tab rods and tab rod ends on the subject models Engine cooling tests conducted subsequent To permit operation of these engines until aircraft are identical in design, hence sus- to the installation of these kits reveal that overhaul, precautionary inspections are nec- ceptible to a similar type of failure, the fol- cylinder head and oll temperature values essary. Inspections in accordance with "A" lowing inspections and tab rod replacements can exceed established limits. To prevent below must be accomplished until the rework or equivalent measures are required. serious damage to the engines in these air- as required by B" below is performed: Compliance required at every 110 hours of craft due to overheating, one of the follow- A. The following inspection of the crank- operation or regular scheduled inspection ing alternate actions is necessary. shafts must be accomplished at least within closest thereto. 1. Remove Reading Aviation Service Inc. 100 hours of operation after November 1956, 1 (a) Inspect the tab rods and tab rod or Hackenberg Aviation Sales and Service and at least every 100 hours of operation ends on the elevator, for looseness in the downdraft cooling kit and return aircraft to thereafter until reworked as required by "B" rivets which attach the rod ends to the rods, the original Ryan cooling configuration, or below: and for any relative movement between the 2. Modify the Reading or Hackenberg en- (1) Remove the propeller, thrust nut cover, rod and the rod end. Parts which exhibit gine cooling kit in accordance with Reading nut, sunger and spacer. these defects shall be replaced with satis- Aviation Service Inc. Service Bulletin No, 1 (2) Carefully clean the area to be in- factory parts. Upon completion of the tab rod dated July 26, 1956. replacement program or equivalent noted in (Sec. 205, 52 Stat. 984, as amended; 49 U.S. C. power optical glass, check for the presence (3) Using a dye penetrant and a six to ten If any crack is found, the crank- inspection may be discontinued. Items 2(a), and 2 (b) below, this 110 hour Compliance required not later than No- 1007, 1009; 49 U.S. C. 551, 553) Interpret or apply sec. 601, 603, 52 Stat. NOTE: In the event of oll leakage in the elevator tab rods with improved, heavier rods 2 (a) Model CV-340 Replacement of all Administrator of Civil Aeronautics. front section of the engine during any opera- and rod ends, and replacement of the right APRIL 4, 1957. scribed above. the inspection procedure de- hand elevator tab idler link with symmetrical Service Bulletin [F. R. Doc. 57-2816; Filed, Apr. 10, 1957; B. As soon as possible, or at the first over- haul after March 1, 1957, the crankshaft is to be subjected to a special magnetic inspec- 2 (b) Model CV-440 Replacement of the tion procedure, shadowgraph inspection, nec- TITLE 15-COMMERCE AND essary radius in the thread root, and shot peening of the thrust bearing nut threaded ends with improved heavier tab rods and tab Convair Service Bulletin Nos. 440- FOREIGN TRADE approved by P&WA will be able to accom- techniques involved, Because of the special equipment and 27A cover this same subject. 72-12A and tAF-12B Helicopters Includ- all UH-12, Chapter II- ards, Department of Commerce -National Bureau of Stand- plish this rework, inspection, and shot peen- Technical Supervisor, Service Department, Pratt & Whitney Aircraft, East Hartford 8, Connecticut" for approval and detail instruc- Interested parties but not later than February 28, 1957. Investigation has revealed that defective Compliance required as soon as possible Subchapter B- -STANDARD SAMPLES AND REFER- -Standard Samples and Reference Crankshafts reworked in accordance welds may exist at the clamp lugs on the ENCE STANDARDS ISSUED BY THE NATIONAL with these special instructions can be identi- four upper lord mount supports on P/N Lower Frame BUREAU OF STANDARDS fed by the marking 14F-56 on the front end Mount), or on mounts, P/N 63100-2M, mod- SUBPART B-STANDARD SAMPLES AND REP- "A" will no longer be required after this is The inspections in accordance with letin No. 51. Failure of this weld has resulted ified in accordance with Hiller Service Bul- in tilting of the rotor mast and loss of col- ERENCE STANDARDS WITH SCHEDULE OF WEIGHTS AND FEES C. After each inspection made in com- lective pitch control. DESCRIPTIVE LIST pliance with "A" and "B" above, a report of the inspection is to be made to Civil Aero- detect possible defective welds which must be inspection is required on the above mounts to In accordance with the provisions of repair station making the inspection should October 10, 1956, covers this subject.) the inspections required by "A" above. Power Plant Branch, W-245, Washington 25, D. C. stating whether the crankshaft is found available, engine model and serial number, and the name and address of the person or essary to determine the continued need for nauties to be in satisfactory or unsatisfactory condi- tion. also be indicated. (P&WA Service Bulletin No. 1488, dated The aircraft registration number, if Administration, This information is nec- Attenion: Chief, reworked as indicated. tionable weldments. and inspect for identification markings in or around the weld at the clamp lugs. no inspection of the weld will be required, fabricated subsequent to the period of ques- plated, remove the paint from all four lord mount supports in the area of the clamp lugs weld is stamped with either a [7] or [8] or move the mount from service until such time since these lower frame assemblies have been no stamp at all, it will be necessary to re- 1. If the engine mount is cadmium plated, 2. If the engine mount is not cadmium If the reason that such procedures, because of base alloys) section 4 (a) and (c) of the Administra- tive Procedure Act, it has been found that notice and hearing on these sched- ules of fees are unnecessary for the the nature of these rules, serve no useful from the date of publication amended to add a new series (Titanium- purpose. FEDERAL REGISTER. Paragraphs These schedules are effective and to retitle and revise (a) through in the are This supersedes AD 54-22-2 and AD as the lugs can be removed and rewelded to paragraphs (e) through (1) to read as 56-23-2. CAM 18 standards. follows: ## Affected data sheets (5) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E-123](https://openairdocs.org/tcds/E-123): Pratt & Whitney Division; names 7 of 7 models: Wasp Jr. T1B3, Wasp Jr. B-4, Wasp Jr. SB-3, Wasp Jr. T1B2, Wasp Jr. SB, Wasp Jr. SB-2, Wasp Jr. B-5 - [TCDS TC 85](https://openairdocs.org/tcds/TC%2085): Pratt & Whitney Division; names 3 of 3 models: Wasp Jr. TB, Wasp Jr. TB-2, Wasp Jr. T3A - [TCDS ATC 39](https://openairdocs.org/tcds/ATC%2039): Pratt & Whitney Division; names 1 of 1 models: Wasp Jr. A - [TCDS TC 113](https://openairdocs.org/tcds/TC%20113): Pratt & Whitney Division; names 1 of 1 models: Wasp Jr. T1B - [TCDS TC 5E-1](https://openairdocs.org/tcds/TC%205E-1): Pratt & Whitney Division; names 1 of 1 models: Military R-985 Series ## Registered aircraft it may apply to (OpenAirDocs) No registered aircraft matched the models it names. It also names AD 54-22-02, which this release has no record of. Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.