# AD 91-09-17: Track Support Bolts - Type: Airworthiness directive - Status: Current - Products: Boeing 737-300 Series and 737-400 Series - Effective: June 3, 1991 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-6984 - Docket: 90-NM-251-AD - Registered aircraft: 30 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/95FB75A9CE81E6A0862569610072D119.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/91-09-17 ## The airworthiness directive 91-09-17 BOEING: Amendment 39-6984. Docket No. 90-NM-251-AD. Supersedes AD 90- 14-04. Applicability: Model 737-300 and -400 series airplanes, line numbers 1001 through 1769 and 1771, as listed in Boeing Alert Service Bulletin 737-57A1202, Revision 1, dated April 26, 1990, certificated in any category. Compliance is required as indicated, unless previously accomplished. To prevent separation of the outboard flap from the airplane, accomplish the following: A. For airplanes line numbers 1001 through 1762: Within the next 30 days after August 25, 1989 (the issuance date of Telegraphic AD T89-18-51), inspect the bolts used to secure the track forward support fitting of the inboard tracks to determine the bolt head designation. B. If a bolt other than Boeing part numbers BACB30LE6 or BACB30LE7, (A286 CRES steel) or BACB30US6 or BACB30US7 (Inconel), is found installed as a result of the inspection required by paragraph A. of this AD, prior to further flight, replace it with a proper bolt and nut in accordance with Boeing Alert Service Bulletin 737-57A1202, dated August 24, 1989, or Revision 1, dated April 26, 1990. C. For airplanes line numbers 1001 through 1762, within the next 1,500 cycles or 6 months after August 6, 1990 (the effective date of amendment 39-6643), whichever occurs first, visually or eddy current inspect the nuts used to secure the track forward support fitting of the inboard track to determine nut material, in accordance with Boeing Alert Service Bulletin 737- 57A1202, dated August 24, 1989, or Revision 1, dated April 26, 1990. NOTE: Inspection of the nuts must be accomplished even if the part numbers of the bolts were previously determined to be correct. D. If a nut other than A286 CRES steel, Boeing part number BACN10HR, is found installed as a result of the inspection required by paragraph C. of this AD, prior to further flight, replace it with a proper nut in accordance with Boeing Alert Service Bulletin 737-57A1202, dated August 24, 1989, or Revision 1, dated April 26, 1990. E. For airplanes line numbers 1763 through 1769 and 1771: Within the next 1,500 cycles or 6 months after the effective date of this Amendment, whichever occurs first, visually or eddy current inspect the nuts used to secure the track forward support fitting of the inboard track to determine the nut material, in accordance with Boeing Alert Service Bulletin 737-57A1202, dated August 24, 1989, or Revision 1, dated April 26, 1990. F. If a nut other than A286 CRES steel, Boeing part number BACN10HR, is found installed as a result of the inspection required by paragraph E. of this AD, prior to further flight, replace it with a proper nut in accordance with Boeing Alert Service Bulletin 737-57A1202, dated August 24, 1989, or Revision 1, dated April 26, 1990. G. 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 Aircraft Certification Office. H. 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. All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. Airworthiness Directive 90-14-04 superseded telegraphic AD T89-18-51. Airworthiness Directive 91-09-17 supersedes AD 90-14-04, Amendment 39-6643. This amendment (39-6984, AD 91-09-17) becomes effective on June 3, 1991. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A16WE](https://openairdocs.org/tcds/A16WE): The Boeing Company; names 2 of 17 models: 737-300 Series, 737-400 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: 30 (30 by airframe model, 0 by engine model) - Makers: Boeing 30 Models with the most aircraft: - [Boeing 737-400](https://openairdocs.org/model/boeing-737-400): 8 aircraft (airframe model) - [Boeing 737-436](https://openairdocs.org/model/boeing-737-436): 6 aircraft (airframe model) - [Boeing 737-300](https://openairdocs.org/model/boeing-737-300): 4 aircraft (airframe model) - [Boeing 737-490](https://openairdocs.org/model/boeing-737-490): 3 aircraft (airframe model) - [Boeing 737-484](https://openairdocs.org/model/boeing-737-484): 3 aircraft (airframe model) - [Boeing 737-301](https://openairdocs.org/model/boeing-737-301): 1 aircraft (airframe model) - [Boeing 737-401](https://openairdocs.org/model/boeing-737-401): 1 aircraft (airframe model) - [Boeing 737-306](https://openairdocs.org/model/boeing-737-306): 1 aircraft (airframe model) - [Boeing 737-319](https://openairdocs.org/model/boeing-737-319): 1 aircraft (airframe model) - [Boeing 737-330](https://openairdocs.org/model/boeing-737-330): 1 aircraft (airframe model) - [Boeing 737-405](https://openairdocs.org/model/boeing-737-405): 1 aircraft (airframe model) All 11 models: https://openairdocs.org/ad/91-09-17/models.md Every aircraft: https://openairdocs.org/ad/91-09-17/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.