# AD 88-23-01: Torque Tube Joints - Type: Airworthiness directive - Status: Current - Products: Mitsubishi Heavy Industries MU-2B, MU-2B-10, MU-2B-15, MU-2B-20, MU-2B-25, MU-2B-26, MU-2B-26A, MU-2B-30, MU-2B-35, MU-2B-36, MU-2B-36A, MU-2B-40 and 1 more - Effective: December 4, 1988 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Amendment: 39-6056 - Registered aircraft: 177 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/92E1378F80FA0A6B86256A4D0049818D.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/88-23-01 ## The airworthiness directive 88-23-01 MITSUBISHI HEAVY INDUSTRIES, LTD. (MHI Amendment 39-6056. Applies to Models MU-2B, MU-2B-10, -15, -20, -25, -26, -26A, -30, -35, -36, -36A, -40, and -60 airplanes (all serial numbers with or without the SA suffix) certificated in any category. Compliance: As indicated in the AD, unless already accomplished. To preclude flap control failure, accomplish the following: (a) On airplanes with more than 4,000 hours Time-in-Service (TIS), within the next 100 hours TIS, and on airplanes with less than 4,000 hours TIS, before reaching 4,100 hours TIS: (1) Inspect torque tube joint Part Number (P/N) 010A-61254, of torque tube assembly P/N 010A-61250 for cracks, and replace a cracked joint with a serviceable unit. If no crack is found, repeat the inspection at intervals not to exceed 100 hours TIS, as follows: (i) For airplanes type certificated in accordance with U. S. Type Certificate (TC) A2PC (those without the serial number suffix SA) as described in MHI MU-2B Service Bulletin (S/B) No. 189B, dated May 27, 1988. (ii) For airplanes type certificated in accordance with U.S. TC A10SW (those airplanes with the serial number suffix SA) as described in MHI MU-2B S/B No. 067/27-008, dated November 16, 1987. (2) Inspect all other torque tube joints listed as "existing joints" in Figure 1 of the applicable S/B for cracks, and replace a cracked joint with a serviceable unit. If no crack is found, repeat the inspection thereafter at intervals not to exceed 500 hours TIS, as follows: (i) For TC A2PC airplanes as described in MHI S/B 189B. (ii) For TC A10SW airplanes as described in MHI S/B No. 067/27-008. (b) Accomplish the inspections and replacement requirements of paragraph (a) of this AD, as applicable, prior to 4,100 hours TIS on each replacement joint listed as an "existing joint," as follows: (1) For TC A2PC airplanes (without S/N suffix SA) in Figure 1 of MHI S/B No. 189B. (2) For TC A10SW airplanes (with S/N suffix SA) in Figure 1of MHI S/B No. 067/27-008. (c) Repetitive inspections of a torque tube joint are terminated upon installation of a joint listed as an "improved joint," as follows: (1) For TC A2PC airplanes (without S/N suffix S/A) in Figure 1 of MHI S/B No. 189B. (2) For TC A10SW airplanes (with S/N suffix SA) in Figure 1 of MHI S/B No. 067/27-008. (d) Airplanes may be flown in accordance with FAR 21.197 to a location where this AD may be accomplished. (e) An equivalent method of compliance with this AD may be used on the A2PC airplanes, if approved by the Manager, Los Angeles Aircraft Certification Office, ANM-120L, FAA, 3229 East Spring Street, Long Beach, California 90806-2425, Telephone (213) 988-5200, and on the A10SW airplanes, if approved by the Manager, Wichita Aircraft Certification Office, ACE-115W, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; Telephone (316) 946-4400. All persons affected by this directive may obtain copies of the documentsreferred to herein upon request to the Beech Aircraft Corporation (Licensee to Mitsubishi), P. O. Box 85, Wichita, Kansas 67201; Telephone (316) 681-9111; or may examine these documents at the FAA, Office of the Assistant Chief Counsel, Room 1558, 601 East 12th Street, Kansas City, Missouri 64106. This amendment, 39-6056, becomes effective on December 4, 1988. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A2PC](https://openairdocs.org/tcds/A2PC): Mitsubishi Heavy Industries Ltd. 203; names 5 of 7 models: MU-2B, MU-2B-30, MU-2B-20, MU-2B-35, MU-2B-36 - [TCDS A10SW](https://openairdocs.org/tcds/A10SW): Mitsubishi Heavy Industries Ltd.; names 4 of 6 models: MU-2B-26A, MU-2B-36A, MU-2B-60, MU-2B-40 ## 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: 177 (177 by airframe model, 0 by engine model) - Makers: Mitsubishi 177 Models with the most aircraft: - [Mitsubishi MU-2B-60](https://openairdocs.org/model/mitsubishi-mu-2b-60): 50 aircraft (airframe model) - [Mitsubishi MU-2B-40](https://openairdocs.org/model/mitsubishi-mu-2b-40): 35 aircraft (airframe model) - [Mitsubishi MU-2B-25](https://openairdocs.org/model/mitsubishi-mu-2b-25): 23 aircraft (airframe model) - [Mitsubishi MU-2B-26A](https://openairdocs.org/model/mitsubishi-mu-2b-26a): 19 aircraft (airframe model) - [Mitsubishi MU-2B-26](https://openairdocs.org/model/mitsubishi-mu-2b-26): 16 aircraft (airframe model) - [Mitsubishi MU-2B-20](https://openairdocs.org/model/mitsubishi-mu-2b-20): 12 aircraft (airframe model) - [Mitsubishi MU-2B-36A](https://openairdocs.org/model/mitsubishi-mu-2b-36a): 10 aircraft (airframe model) - [Mitsubishi MU-2B-36](https://openairdocs.org/model/mitsubishi-mu-2b-36): 7 aircraft (airframe model) - [Mitsubishi MU-2B-35](https://openairdocs.org/model/mitsubishi-mu-2b-35): 4 aircraft (airframe model) - [Mitsubishi MU-2B](https://openairdocs.org/model/mitsubishi-mu-2b): 1 aircraft (airframe model) All 10 models: https://openairdocs.org/ad/88-23-01/models.md Every aircraft: https://openairdocs.org/ad/88-23-01/aircraft.md Its text cites no advisory circulars or STCs. ## NTSB investigations that cite this AD (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB MIA01FA206](https://openairdocs.org/ntsb/MIA01FA206), Aug 1, 2001: Mitsubishi MU-2B-35 (N1VY), Hilton Head, SC, destroyed, 1 fatal. Probable cause: Improper maintenance/installation and and inadequate inspection of the airplane's flap torque tube joints during routine maintenance by company maintenance personnel, which resulted in the right flap… --- 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.