# AD 75-15-06: Landing Gear Struts - Type: Airworthiness directive - Status: Current - Products: Learjet 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25 and 5 more - Effective: July 25, 1975 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-2267 - Registered aircraft: 72 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/182CD94F4DD7CAFA8625696E005429C0.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/75-15-06 ## The airworthiness directive 75-15-06 GATES LEARJET: Amendment 39-2267. Applies to 23 (Serial Numbers 23- 003 thru 23-099); 24 (Serial Numbers 24-100 thru 24-297); and 25 (Serial Numbers 25-003 thru 25-182) series airplanes. Compliance: Required as indicated, unless already accomplished in accordance with Gates Learjet Service Bulletin No. SB 23/24/25-259A or later approved revisions. To check for flaws in the upper main landing gear struts, accomplish the following: A) Within the next 600 hours' time in service after the effective date of this AD, but not later than September 30, 1976, using eddy current or ultrasonic inspection equipment and procedures, inspect the left and right upper main landing gear struts for flaws in accordance with the instructions and sketches outlined in Gates Learjet Service Bulletin No. SB 23/24/25-259A or later approved revisions, or alternatively, remove the left and right upper landing gear struts from the airplane, disassemble, clean, and inspect the struts forflaws in accordance with the aforementioned Service Bulletin. B) If, as a result of the inspections referred to in Paragraph A, flaws are detected, within the next 50 hours' time in service, accomplish the following: 1. Remove any flaw in an upper main landing gear strut with a depth less than .025 inches in accordance with the procedures outlined in the aforementioned Service Bulletin. a. After flaw removal, reinspect using eddy current or ultrasonic methods to assure complete removal of the flaw and then treat and paint the affected area in accordance with the aforementioned Service Bulletin. 2. For flaws that exceed a depth of .025 inches, modify the upper main landing gear strut in accordance with instructions provided by the manufacturer or alternatively, replace with an airworthy part. C) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. NOTE: Aircraft inspected and in compliance with Gates Learjet Service Bulletin SB 23/24/25-259 (i.e., the original Service Bulletin on this subject) are considered to have complied with the requirements of this AD. This amendment becomes effective July 25, 1975. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A10CE](https://openairdocs.org/tcds/A10CE): Learjet Inc.; names 16 of 29 models: 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E… - [TCDS A5CE](https://openairdocs.org/tcds/A5CE): Learjet Inc.; names 1 of 1 models: 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: 72 (72 by airframe model, 0 by engine model) - Makers: Gates Lear Jet 27, Learjet 25, Gates Learjet 20 Models with the most aircraft: - [Gates Learjet 25D](https://openairdocs.org/model/gates-learjet-25d): 20 aircraft (airframe model) - [Gates Lear Jet 25B](https://openairdocs.org/model/gates-lear-jet-25b): 12 aircraft (airframe model) - [Learjet 24](https://openairdocs.org/model/learjet-24): 7 aircraft (airframe model) - [Gates Lear Jet 24D](https://openairdocs.org/model/gates-lear-jet-24d): 7 aircraft (airframe model) - [Learjet 23](https://openairdocs.org/model/learjet-23): 6 aircraft (airframe model) - [Learjet 24D](https://openairdocs.org/model/learjet-24d): 4 aircraft (airframe model) - [Gates Lear Jet 24F](https://openairdocs.org/model/gates-lear-jet-24f): 4 aircraft (airframe model) - [Learjet 24B](https://openairdocs.org/model/learjet-24b): 3 aircraft (airframe model) - [Learjet 24A](https://openairdocs.org/model/learjet-24a): 2 aircraft (airframe model) - [Gates Lear Jet 24E](https://openairdocs.org/model/gates-lear-jet-24e): 2 aircraft (airframe model) - [Learjet 25](https://openairdocs.org/model/learjet-25): 2 aircraft (airframe model) - [Gates Lear Jet 25](https://openairdocs.org/model/gates-lear-jet-25): 1 aircraft (airframe model) - [Gates Lear Jet 25C](https://openairdocs.org/model/gates-lear-jet-25c): 1 aircraft (airframe model) - [Learjet 25D](https://openairdocs.org/model/learjet-25d): 1 aircraft (airframe model) All 14 models: https://openairdocs.org/ad/75-15-06/models.md Every aircraft: https://openairdocs.org/ad/75-15-06/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.