# AD 72-12-01: Main Landing Gear Downlock Torque Shaft - Type: Airworthiness directive - Status: Current - Products: Boeing 727-100 Series, 727-100C Series, 727-200 Series, 727-200F Series, 727 Series and 727C Series - Effective: May 3, 1976 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-2576 - Registered aircraft: 25 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/BC58E4159E903C9086256E0D00491D95.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/72-12-01 ## The airworthiness directive 72-12-01 BOEING: Amendment 39-1456 as amended by Amendment 39-2026, 39-2353 and 39-2410 is further amended by Amendment 39-2576. Applies to all model 727 series airplanes listed in Boeing Service Bulletin No. 32-180, Revision 1, or later FAA-approved revisions, incorporating main landing gear downlock torque shaft P/N 65-23366. Compliance required as indicated: To detect cracks in the main landing gear downlock torque shaft, accomplish the following: (a) For all torque shafts which have accumulated 8,000 or more landing cycles on the effective date of Amendment 39-2353, inspect the shaft within the next 300 landings after the effective date of Amendment 39-2353, unless already accomplished within the last 100 landings, and thereafter at intervals not to exceed 400 landings since the last inspection, per (b) below, until the shaft is replaced per (c) below. (b) Inspect the shaft in accordance with Boeing Service Bulletin No. 32-180, Revision 1, or later FAA-approved revisions, or an equivalent inspection approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. If evidence of a crack is found, replace the shaft prior to further flight with an improved shaft P/N 65-78698 in accordance with Boeing Service Bulletin Nos. 32-180, Revision 1, or 727-32-237, or later FAA approved revisions, or with a shaft that (1) has accumulated less than 8,000 landing cycles, or (2) has been previously inspected per this AD. (c) Replace shafts per Boeing Service Bulletin Nos. 32-180, Revision 1, or 727-32-237, or later FAA-approved revisions, or an equivalent replacement procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. (d) For the purpose of this AD, when conclusive records are not available to show the number of landings accumulated by a particular shaft, the number of landings may be computed by dividing the airplane time in service since the shaft was installed in the airplane by the operator's fleet average time per flight for his model 727 airplanes. (e) Installations of main landing gear downlock torque shafts, P/N 65-78698, in accordance with Boeing Service Bulletin Nos. 32-180, Revision 1, or 727-32-237, or later FAA approved revisions, or an equivalent installation approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, constitutes terminating action from the provisions of this AD. (f) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for that operator. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. The documents may also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington. Amendment 39-1456 became effective July 3, 1972. Amendment 39-2026 became effective December 2, 1974. Amendment 39-2353 became effective September 29, 1975. Amendment 39-2410 became effective December 4, 1975. This amendment 39-2576 becomes effective May 3, 1976. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A3WE](https://openairdocs.org/tcds/A3WE): The Boeing Company; names 6 of 6 models: 727-100 Series, 727 Series, 727-200 Series, 727-100C Series, 727-200F Series, 727C Series ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 25 (25 by airframe model, 0 by engine model) - Makers: Boeing 25 Models with the most aircraft: - [Boeing 727-223](https://openairdocs.org/model/boeing-727-223): 9 aircraft (airframe model) - [Boeing 727-227](https://openairdocs.org/model/boeing-727-227): 4 aircraft (airframe model) - [Boeing 727-225](https://openairdocs.org/model/boeing-727-225): 2 aircraft (airframe model) - [Boeing 727-200F](https://openairdocs.org/model/boeing-727-200f): 1 aircraft (airframe model) - [Boeing 727-200](https://openairdocs.org/model/boeing-727-200): 1 aircraft (airframe model) - [Boeing 727-212](https://openairdocs.org/model/boeing-727-212): 1 aircraft (airframe model) - [Boeing 727-230](https://openairdocs.org/model/boeing-727-230): 1 aircraft (airframe model) - [Boeing 727-232](https://openairdocs.org/model/boeing-727-232): 1 aircraft (airframe model) - [Boeing 727-243](https://openairdocs.org/model/boeing-727-243): 1 aircraft (airframe model) - [Boeing 727-247](https://openairdocs.org/model/boeing-727-247): 1 aircraft (airframe model) - [Boeing 727-264](https://openairdocs.org/model/boeing-727-264): 1 aircraft (airframe model) - [Boeing 727-281](https://openairdocs.org/model/boeing-727-281): 1 aircraft (airframe model) - [Boeing 727-277](https://openairdocs.org/model/boeing-727-277): 1 aircraft (airframe model) All 13 models: https://openairdocs.org/ad/72-12-01/models.md Every aircraft: https://openairdocs.org/ad/72-12-01/aircraft.md 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.