# SAIB NM-13-38: Flight Controls Control Column Section - Type: Special airworthiness information bulletin (advisory, not mandatory) - Status: Current - Revision: 0 - Issued: June 24, 2013 - Products: Learjet 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25 and 13 more - Product type: Aircraft, Large Airplane - PDF: https://openairdocs.org/files/sha256/95/ec/95ec27fa104597b9f8b0b4d2c6d0f641de7b82d637d68dba41b990904a2f69c7 - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/A7C31B952DBB5BED86257B940052F851.0001 - DRS record last changed: June 24, 2013 - Page: https://openairdocs.org/saib/NM-13-38 ## Text FAA Aviation Safety **SPECIAL AIRWORTHINESS** INFORMATION BULLETIN SUBJ: Flight Controls – Control Column Section SAIB: NM-13-38 Date: June 24, 2013 This is information only. Recommendations aren’t mandatory. Introduction This Special Airworthiness Information Bulletin (SAIB) informs owners, operators, and maintenance personnel of Learjet Inc. Model 23 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F, 28, 29, 31, 31A, 35, 35A (C-21A), 36, and 36A airplanes of an airworthiness concern regarding possible cracking in the control column of the flight controls. At this time, the airworthiness concern is not an unsafe condition that would warrant Airworthiness Directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) Part 39. Background Maintenance personnel reported finding cracks in the control column on Learjet Model 35A (C-21A) airplanes. Five airplanes were inspected and all five had cracks in the same general area. The cracks all originated at the base of the column where it attaches to the floor structure. The bearing boss where a pivot pin is installed was partially cracked in all cases. This detail is typical for both the lefthand and right-hand sides of the control column. Investigation of the cracking on these airplanes by both Learjet and FAA personnel revealed that a portion of the bearing boss was cracked, and the pivot pin remained intact with no jamming of the control system. Learjet has issued the following Service Bulletins for the affected airplanes: • SB 23/24/25-27-12 Revision 2, dated October 26, 2009. • SB 23/24/25-27-24, dated December 17, 2012. • SB 28/29-27-29, dated December 17, 2012. • SB 31-27-33, dated December 17, 2012. • SB 35/36-27-48, dated December 17, 2012. The service bulletins specify inspecting the control column for cracks and replacing the control column assembly, including repair reinforcement of the bearing boss which supports the pivot pin. Recommendations The FAA recommends that all owners and operators of the Learjet airplanes identified above follow the actions outlined in the above service information, at the earliest opportunity. For Further Information Contact Paul Chapman, Aerospace Engineer, Airframe and Services Branch, ACE-118W, FAA, Wichita Aircraft Certification Office; 1801 Airport Road, Room 100, Mid-continent Airport, Wichita, Kansas 67209; phone: 316 946-4152; fax: 316 946-4129; email: paul.chapman@faa.gov. 2 (Optional) For Related Service Information Contact Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942; telephone 316-946-2000; fax 316-946-2220; email ac.ict@aero.bombardier.com; Internet http://www.bombardier.com. ## Registered aircraft it may concern (OpenAirDocs) Registry models matched by make and model, the same way as ADs, most registered aircraft first. - [Gates Learjet 35A](https://openairdocs.org/model/gates-learjet-35a): 135 registered aircraft (airframe model) - [Learjet 31A](https://openairdocs.org/model/learjet-31a): 104 registered aircraft (airframe model) - [Learjet 35A](https://openairdocs.org/model/learjet-35a): 24 registered aircraft (airframe model) - [Gates Lear Jet 36A](https://openairdocs.org/model/gates-lear-jet-36a): 21 registered aircraft (airframe model) - [Gates Learjet 25D](https://openairdocs.org/model/gates-learjet-25d): 20 registered aircraft (airframe model) - [Gates Lear Jet 35](https://openairdocs.org/model/gates-lear-jet-35): 16 registered aircraft (airframe model) - [Learjet 31](https://openairdocs.org/model/learjet-31): 15 registered aircraft (airframe model) - [Gates Lear Jet 36](https://openairdocs.org/model/gates-lear-jet-36): 13 registered aircraft (airframe model) - [Gates Lear Jet 25B](https://openairdocs.org/model/gates-lear-jet-25b): 12 registered aircraft (airframe model) - [Gates Lear Jet 24D](https://openairdocs.org/model/gates-lear-jet-24d): 7 registered aircraft (airframe model) - [Learjet 24](https://openairdocs.org/model/learjet-24): 7 registered aircraft (airframe model) - [Learjet 23](https://openairdocs.org/model/learjet-23): 6 registered aircraft (airframe model) - [Gates Lear Jet 24F](https://openairdocs.org/model/gates-lear-jet-24f): 4 registered aircraft (airframe model) - [Learjet 24D](https://openairdocs.org/model/learjet-24d): 4 registered aircraft (airframe model) - [Gates Lear Jet 28](https://openairdocs.org/model/gates-lear-jet-28): 3 registered aircraft (airframe model) - [Learjet 24B](https://openairdocs.org/model/learjet-24b): 3 registered aircraft (airframe model) - [Gates Lear Jet 24E](https://openairdocs.org/model/gates-lear-jet-24e): 2 registered aircraft (airframe model) - [Learjet 24A](https://openairdocs.org/model/learjet-24a): 2 registered aircraft (airframe model) - [Learjet 25](https://openairdocs.org/model/learjet-25): 2 registered aircraft (airframe model) - [Gates Lear Jet 25](https://openairdocs.org/model/gates-lear-jet-25): 1 registered aircraft (airframe model) - [Gates Lear Jet 25C](https://openairdocs.org/model/gates-lear-jet-25c): 1 registered aircraft (airframe model) - [Gates Learjet 35A (C-21A)](https://openairdocs.org/model/gates-learjet-35a-c-21a): 1 registered aircraft (airframe model) - [Learjet 25D](https://openairdocs.org/model/learjet-25d): 1 registered aircraft (airframe model) - [Learjet 35](https://openairdocs.org/model/learjet-35): 1 registered aircraft (airframe model) - [Gates Lear Jet 24B](https://openairdocs.org/model/gates-lear-jet-24b): 0 registered aircraft (airframe model) - [Gates Lear Jet 24B-A](https://openairdocs.org/model/gates-lear-jet-24b-a): 0 registered aircraft (airframe model) - [Gates Lear Jet 24C](https://openairdocs.org/model/gates-lear-jet-24c): 0 registered aircraft (airframe model) - [Gates Lear Jet 24D-A](https://openairdocs.org/model/gates-lear-jet-24d-a): 0 registered aircraft (airframe model) - [Gates Lear Jet 25F](https://openairdocs.org/model/gates-lear-jet-25f): 0 registered aircraft (airframe model) - [Gates Lear Jet 29](https://openairdocs.org/model/gates-lear-jet-29): 0 registered aircraft (airframe model) - [Gates Learjet 24](https://openairdocs.org/model/gates-learjet-24): 0 registered aircraft (airframe model) - [Learjet 24F-A](https://openairdocs.org/model/learjet-24f-a): 0 registered aircraft (airframe model) --- 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.