# AD 91-23-09: Electrical Power System - Type: Airworthiness directive - Status: Current - Products: Boeing 747-400 Series and 747-400D Series - Effective: November 27, 1991 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-8078 - Docket: 91-NM-199-AD - Registered aircraft: 38 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/B38FAA9903E1F685862569610072DF03.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/91-23-09 ## The airworthiness directive 91-23-09 BOEING: Amendment 39-8078. Docket No. 91-NM-199-AD. Applicability: Model 747-400 series airplanes; line numbers 813 through 845, inclusive; certificated in any category. Compliance: Required within 20 days after the effective date of this AD, unless previously accomplished. To prevent fire due to overheated terminals and/or the loss of power to the standby electrical power system, accomplish the following: (a) Inspect the nuts on terminal strips TD469 and TD470, located in the P180-1 panel, for proper torque of 65 to 75 inch-pounds, in accordance with Boeing Commercial Airplane Group Process Specification BAC 5159, Revision F, dated March 1, 1991. If any nut is found not to have proper torque, prior to further flight, re-torque the nut to 65 to 75 inch-pounds, in accordance with the Boeing Process Specification. (b) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO. (c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. (d) The inspection and re-torquing requirements shall be done in accordance with Boeing Commercial Airplane Group Process Specification BAC 5159, Revision F, dated March 1, 1991. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington, or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C. This amendment (39-8078, AD 91-23-09) becomes effective on November 27, 1991. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A20WE](https://openairdocs.org/tcds/A20WE): The Boeing Company; names 2 of 14 models: 747-400D Series, 747-400 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: 38 (38 by airframe model, 0 by engine model) - Makers: Boeing 38 Models with the most aircraft: - [Boeing 747-446](https://openairdocs.org/model/boeing-747-446): 10 aircraft (airframe model) - [Boeing 747-422](https://openairdocs.org/model/boeing-747-422): 8 aircraft (airframe model) - [Boeing 747-412](https://openairdocs.org/model/boeing-747-412): 5 aircraft (airframe model) - [Boeing 747-409](https://openairdocs.org/model/boeing-747-409): 4 aircraft (airframe model) - [Boeing 747-481](https://openairdocs.org/model/boeing-747-481): 3 aircraft (airframe model) - [Boeing 747-443](https://openairdocs.org/model/boeing-747-443): 2 aircraft (airframe model) - [Boeing 747-438](https://openairdocs.org/model/boeing-747-438): 2 aircraft (airframe model) - [Boeing 747-428](https://openairdocs.org/model/boeing-747-428): 2 aircraft (airframe model) - [Boeing 747-400](https://openairdocs.org/model/boeing-747-400): 1 aircraft (airframe model) - [Boeing 747-451](https://openairdocs.org/model/boeing-747-451): 1 aircraft (airframe model) All 10 models: https://openairdocs.org/ad/91-23-09/models.md Every aircraft: https://openairdocs.org/ad/91-23-09/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.