# AD 66-23-01: B-nuts at the Engine Firewall - Type: Airworthiness directive - Status: Current - Products: Boeing 727-100 Series, 727-100C Series, 727-200 Series, 727-200F Series, 727 Series and 727C Series - Effective: October 16, 1966 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-288 - Registered aircraft: 25 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9B48A311D2C75ABD8625682E005ABF48.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/66-23-01 ## The airworthiness directive 66-23-01 BOEING: Admit. 39-288 Part 39 Federal Register September 16, 1966. Applies to Model 727 Series Airplanes Listed in Boeing Service Bulletin 28-25, Revision 1, Dated January 19, 1966. Compliance required as indicated, unless already accomplished. It has been determined that certain of the B-nuts at the engine firewall on Boeing Model 727 Series airplanes are susceptible to cracking. To correct this condition: (a) Within the next 600 hours' time in service after the effective date of this AD, inspect the engine fuel feed system B-nut, P/N NAS596, located at each engine firewall to determine if it is an AFCO (Aircraft Fitting, Inc.) manufactured part. Identification must be made in accordance with the instructions listed in Boeing Service Bulletin 28-25, dated December 3, 1965, or later FAA-approved revision. (b) If the B-nut is not an AFCO part, no further action under this AD is required. If the B-nut is an AFCO part, accomplish the following before further flight: (1) Inspect for cracks using a 10-power glass, dye penetrant or ultrasonic method. (2) If cracks are found, remove the fuel line tube assembly and replace with a new part in accordance with Boeing Service Bulletin 28-25, dated December 3, 1965, or later FAA- approved revision or an equivalent approved by the Chief, Aircraft Engineering Division, FAA Western Region. (3) If no cracks are found, repeat the inspection required under (1) every 600 hours' time in service until the AFCO B-nuts are replaced as specified in (c). (c) Within the next 3,000 hours' time in service after the effective date of this AD, unless already accomplished under (b), remove all fuel feed line tube assemblies incorporating AFCO B-nuts and replace in accordance with Boeing Service Bulletin 28-25, dated December 3, 1965, or later FAA-approved revision or an equivalent approved by the Chief, Aircraft Engineering Division, FAA Western Region. (d) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Aircraft Engineering Division, FAA Western Region, may adjust the repetitive inspection period of the operator if the request contains substantiating data to justify the increase for that operator. This directive effective October 16, 1966. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A3WE](https://openairdocs.org/tcds/A3WE): The Boeing Company; names 6 of 6 models: 727-100 Series, 727 Series, 727-200 Series, 727-100C Series, 727-200F Series, 727C Series ## 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: 25 (25 by airframe model, 0 by engine model) - Makers: Boeing 25 Models with the most aircraft: - [Boeing 727-223](https://openairdocs.org/model/boeing-727-223): 9 aircraft (airframe model) - [Boeing 727-227](https://openairdocs.org/model/boeing-727-227): 4 aircraft (airframe model) - [Boeing 727-225](https://openairdocs.org/model/boeing-727-225): 2 aircraft (airframe model) - [Boeing 727-200F](https://openairdocs.org/model/boeing-727-200f): 1 aircraft (airframe model) - [Boeing 727-200](https://openairdocs.org/model/boeing-727-200): 1 aircraft (airframe model) - [Boeing 727-212](https://openairdocs.org/model/boeing-727-212): 1 aircraft (airframe model) - [Boeing 727-230](https://openairdocs.org/model/boeing-727-230): 1 aircraft (airframe model) - [Boeing 727-232](https://openairdocs.org/model/boeing-727-232): 1 aircraft (airframe model) - [Boeing 727-243](https://openairdocs.org/model/boeing-727-243): 1 aircraft (airframe model) - [Boeing 727-247](https://openairdocs.org/model/boeing-727-247): 1 aircraft (airframe model) - [Boeing 727-264](https://openairdocs.org/model/boeing-727-264): 1 aircraft (airframe model) - [Boeing 727-281](https://openairdocs.org/model/boeing-727-281): 1 aircraft (airframe model) - [Boeing 727-277](https://openairdocs.org/model/boeing-727-277): 1 aircraft (airframe model) All 13 models: https://openairdocs.org/ad/66-23-01/models.md Every aircraft: https://openairdocs.org/ad/66-23-01/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.