# AD 78-16-03: Refrigeration Condenser Fan - Type: Airworthiness directive - Status: Current - Products: Learjet 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25 and 9 more - Effective: August 17, 1978 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-3278 - Registered aircraft: 283 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/6CF76879677A5B968625696E00542B94.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/78-16-03 ## The airworthiness directive 78-16-03 LEARJET: Amendment 39-3278. Applies to Learjet Model 23 (Serial Numbers 23-003 and up); Model 24 and 24A (Serial Numbers 24-100 through 24-180); Model 24B and 24B-A (Serial Numbers 24-181 through 24-229); Model 24C, 24D and 24D-A (Serial Numbers 24-218, and 24-230 through 24-328); Model 24E, 24F and 24F-A (Serial Numbers 24- 329 through 24-356); Model 25 and 25A (Serial Numbers 25-002 through 25-066); Model 25B and 25C (Serial Numbers 25-061, 25-067 through 25-201, 25-204 and 25-205); Model 25D and 25F (Serial Numbers 25-206 through 25-253); Model 35 (Serial Numbers 35-001 through 35- 066); Model 35A (Serial Numbers 35-067 through 35-194); Model 36 (Serial Numbers 36-001 through 36-017); and Model 36A (Serial Numbers 36-018 through 36-040) airplanes. COMPLIANCE: Required as indicated unless already accomplished. To preclude a failure of the refrigeration condenser fan: A) Before the next flight, remove or lower the tailcone access door, disconnect the aircraft batteries, and inspect the refrigeration condenser fan part number that is rubber stamped on the blade. If the refrigeration condenser fan installed has a part number other than 6608059-3, no further action is required. (The blades on P/N 6608059-3 fans are not tapered in thickness from the hub to the tip.) B) If Part Number 6608059-3 refrigeration condenser fan is installed, before the next flight fabricate a placard which reads "DO NOT OPERATE REFRIGERATION SYSTEM UNDER ANY CIRCUMSTANCES ON THE GROUND OR IN THE AIR." Install this placard as near as possible to the refrigeration system control switch and operate the airplane in accordance with this restriction. C) When the Part Number 6608059-3 fan is replaced with either a P/N 6608059-1, 6608059-2 or a P/N 6608059-4 fan, the above required placard may be removed and the airplane returned to normal service. (The blades on the -1, -2 and -4 fans are tapered in thickness from the hub to the tip.) D) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. NOTE: Gates Learjet Service Bulletins SB23/24/25-284, dated 7/13/78, and SB35/36- 21-3, dated 7/12/78, or later approved revisions, provide inspection and fan replacement procedures, physical characteristics of the fans, and replacement part credit information. This amendment becomes effective August 17, 1978, to all persons except those to whom it has already been made effective by air mail letter from the FAA dated July 21, 1978. ## 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 20 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: 283 (283 by airframe model, 0 by engine model) - Makers: Gates Learjet 156, Gates Lear Jet 77, Learjet 50 Models with the most aircraft: - [Gates Learjet 35A](https://openairdocs.org/model/gates-learjet-35a): 135 aircraft (airframe model) - [Learjet 35A](https://openairdocs.org/model/learjet-35a): 24 aircraft (airframe model) - [Gates Lear Jet 36A](https://openairdocs.org/model/gates-lear-jet-36a): 21 aircraft (airframe model) - [Gates Learjet 25D](https://openairdocs.org/model/gates-learjet-25d): 20 aircraft (airframe model) - [Gates Lear Jet 35](https://openairdocs.org/model/gates-lear-jet-35): 16 aircraft (airframe model) - [Gates Lear Jet 36](https://openairdocs.org/model/gates-lear-jet-36): 13 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) - [Learjet 35](https://openairdocs.org/model/learjet-35): 1 aircraft (airframe model) All 22 models: https://openairdocs.org/ad/78-16-03/models.md Every aircraft: https://openairdocs.org/ad/78-16-03/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.