AD 91-18-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-400 Series | Airworthiness Directives; BOEING Model 747-400 Series Airplanes |
Unsafe Condition
Loss of essential airplane electrical busses due to inadequate separation between wiring associated with differential protection current transformers for AC channels 1, 2, and 3 in the P6 panel.
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Required Actions
Reroute and add protective sleeving to wiring associated with differential protection current transformers for AC channels 1, 2, and 3 in the P6 panel per Boeing Service Bulletin 747-24-2154. Alternative methods or compliance time adjustments require FAA approval. Special flight permits may be issued under FAR 21.197 and 21.199.
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Compliance Time
within 180 days after the effective date of this AD, unless previously accomplished
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Affected Aircraft
Boeing Model 747-400 series airplanes listed in Boeing Service Bulletin 747-24-2154 dated February 7, 1991, certificated in any category.
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Federal Register Abstract
Electrical Busses
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_91-18-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 91-18-05 Document Type: AD Final Rules Docket Number: 91-NM-61-AD Subject Heading: Airworthiness Directives; BOEING Model 747-400 Series Airplanes Subject: Electrical Busses Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 09/20/1991 Make: The Boeing Company Model: 747-400 Series Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 91-18-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: 91-NM-61-AD AMENDMENT: 39-8008 AD NUMBER: 91-18-05 SUBJECT HEADING: Airworthiness Directives; BOEING Model 747-400 Series Airplanes ACTION: SUMMARY: DATES: Effective September 20, 1991. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 91-18-05 BOEING: Amendment 39-8008. Docket No. 91-NM-61-AD. Applicability: Model 747-400 series airplanes, listed in Boeing Service Bulletin 747-24- 2154, dated February 7, 1991, certificated in any category. Compliance: Required within 180 days after the effective date of this AD, unless previously accomplished. To prevent the loss of essential airplane electrical busses, accomplish the following: A. Reroute and add protective sleeving to provide adequate separation between wiring associated with the differential protection current transformers for AC channels 1, 2, and 3, located in the P6 panel, in accordance with Boeing Service Bulletin 747-24-2154, dated February 7, 1991. 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 modification requirements shall be done in accordance with Boeing Service Bulletin 747-24-2154 dated February 7, 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 SW., Renton, Washington, or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, D.C. This amendment (39-8008, AD 91-18-05) becomes effective on September 20, 1991. FOOTER:
Document Text
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AD Final Rules - DRS_91-18-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 91-18-05 Document Type: AD Final Rules Docket Number: 91-NM-61-AD Subject Heading: Airworthiness Directives; BOEING Model 747-400 Series Airplanes Subject: Electrical Busses Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 09/20/1991 Make: The Boeing Company Model: 747-400 Series Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 91-18-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: 91-NM-61-AD AMENDMENT: 39-8008 AD NUMBER: 91-18-05 SUBJECT HEADING: Airworthiness Directives; BOEING Model 747-400 Series Airplanes ACTION: SUMMARY: DATES: Effective September 20, 1991. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 91-18-05 BOEING: Amendment 39-8008. Docket No. 91-NM-61-AD. Applicability: Model 747-400 series airplanes, listed in Boeing Service Bulletin 747-24- 2154, dated February 7, 1991, certificated in any category. Compliance: Required within 180 days after the effective date of this AD, unless previously accomplished. To prevent the loss of essential airplane electrical busses, accomplish the following: A. Reroute and add protective sleeving to provide adequate separation between wiring associated with the differential protection current transformers for AC channels 1, 2, and 3, located in the P6 panel, in accordance with Boeing Service Bulletin 747-24-2154, dated February 7, 1991. 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 modification requirements shall be done in accordance with Boeing Service Bulletin 747-24-2154 dated February 7, 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 SW., Renton, Washington, or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, D.C. This amendment (39-8008, AD 91-18-05) becomes effective on September 20, 1991. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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