# AD 81-04-05 R1: Flap-Spar Hinge Attachment - Type: Airworthiness directive - Status: Current - Products: Piper PA-23, PA-23-235, PA-23-250 and PA-23-250 (Navy UO-1) - Effective: February 11, 1982 - Published: February 8, 1982 - Issued: January 28, 1982 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Amendment: 39-4312 - Registered aircraft: 1,079 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DB4E857DB9905667862569A6005CDB13.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/81-04-05-R1 ## The airworthiness directive 81-04-05 R1 PIPER: Amendment 39-4040 as amended by amendment 39-4312. Applies to the following Piper PA-23 Series airplanes certificated in all categories: PA-23 S/N 23-1 thru 23-2046 PA-23-235 S/N 27-505 thru 27-622 PA-23-250 S/N 27-1 thru 27-504 PA-23-250 (6 place) S/N 27-2000 thru 27-8054059 (a) To prevent malfunctioning of the flaps comply with the following: (1) For all referenced airplanes except PA-23-250s (6 place) above S/N 27- 7405300, inspect the flap-spar hinge attachment areas for cracks and repair if necessary in accordance with the instructions paragraph of Piper Service Letter No. 853 dated June 8, 1979, or equivalent as follows: (i) Airplanes with more than 2000 hours in service but not exceeding 3000 hours, inspect and repair if necessary within the next 100 hours in service and thereafter at intervals not to exceed 100 hours in service since the last inspection. (ii) Airplanes with more than 3000 hours in service, inspect and repair if necessary, within the next 50 hours in service, unless already inspected within the last 50 hours in service, and thereafter at intervals not to exceed 100 hours in service since the last inspection. (2) When the flaps are replaced by the appropriate flaps in accordance with the part numbers in the Materials Required section in Piper Service Letter No. 853 dated June 8, 1979, or equivalent, further compliance with (a) is not required. (b) To prevent malfunctioning of the flap control system, comply with the following: (1) For all referenced airplanes, inspect the flap control system for cracks and repair if necessary in accordance with steps 1 through 13 under "instructions" in Piper Service Bulletin No. 671 dated October 20, 1980 or equivalent, and alter in accordance with step 9, as follows: (i) Airplanes with more than 1000 hours in service but not exceeding 2000 hours, comply with (b)(1) within the next 100 hours in service, unless already accomplished. (ii) Airplanes with more than 2000 hours in service, comply with (b)(1) within the next 50 hours in service, unless already accomplished. (2) After the bellcrank, Piper Number 16423-00, is reassembled in accordance with 4e in Service Bulletin 671, conduct a visual inspection of the bellcrank for cracks at intervals not to exceed 100 hours in service after the initial inspection of step 4. If cracks are found replace with new bellcrank Piper P/N 16423-06, or equivalent, before further flight. Upon installation of bellcrank Piper P/N 16423-06, or equivalent, the repetitive inspections are no longer required. Equivalent inspections, parts and alterations must be approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Upon submittal of substantiating data by an owner or operator through an FAA Maintenance Inspector, the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may adjust the compliance times specified in this AD. Amendment 39-4040 was effective February 12, 1981. This amendment 39-4312 is effective February 11, 1982. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 1A10](https://openairdocs.org/tcds/1A10): Piper Aircraft Inc.; names 3 of 6 models: PA-23-235, PA-23-250 (Navy UO-1), PA-23 ## 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: 1,079 (1,079 by airframe model, 0 by engine model) - Makers: Piper 1,079 Models with the most aircraft: - [Piper PA-23-250](https://openairdocs.org/model/piper-pa-23-250): 894 aircraft (airframe model) - [Piper PA-23](https://openairdocs.org/model/piper-pa-23): 155 aircraft (airframe model) - [Piper PA-23-235](https://openairdocs.org/model/piper-pa-23-235): 25 aircraft (airframe model) - [Piper PA-23-250 (6PCLM)](https://openairdocs.org/model/piper-pa-23-250-6pclm): 5 aircraft (airframe model) All 4 models: https://openairdocs.org/ad/81-04-05-R1/models.md Every aircraft: https://openairdocs.org/ad/81-04-05-R1/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.