# Airworthiness Directives; Boeing Model 747 Series Airplanes Equipped With General Electric Model CF6-45 or -50 Series Engines; or Pratt & Whitney Model JT9D-3, -7, or -70 Series Engines; and 747-E4B (Military) Airplanes
> **Rule** · Final rule; request for comments. · Published 1999-04-23 · Effective 1999-05-10 · 64 FR 19883
## Document
- **Document number:** 99-10175
- **Category:** airworthiness
- **Manufacturer:** Boeing Model 747 Series
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 64 FR 19883
- **Publication date:** 1999-04-23
- **Effective date:** 1999-05-10
- **FAA docket:** Docket No. 99-NM-49-AD
## Abstract

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes and all 747- E4B (military) airplanes. This action requires repetitive inspections to detect cracking or fracture of the steel attachment fittings of the diagonal brace to the nacelle struts; and replacement of the attachment fittings with new steel fittings, if necessary. This amendment is prompted by a report indicating a fractured steel attachment fitting of a diagonal brace to the number 2 nacelle strut; such fracture has been attributed to fatigue cracking. The actions specified in this AD are intended to detect and correct such fatigue cracking, which could result in failure of a nacelle strut diagonal brace load path and possible separation of the nacelle from the wing.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1999/04/23/99-10175/airworthiness-directives-boeing-model-747-series-airplanes-equipped-with-general-electric-model)
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