# Airworthiness Directives; Boeing Model 747 Series Airplanes
> **Rule** · Final rule. · Published 1999-01-07 · Effective 1999-02-11 · 64 FR 985
## Document
- **Document number:** 99-186
- **Category:** airworthiness
- **Manufacturer:** Boeing Model 747 Series
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 64 FR 985
- **Publication date:** 1999-01-07
- **Effective date:** 1999-02-11
- **FAA docket:** Docket No. 97-NM-308-AD
## Abstract

This amendment revises an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires repetitive inspections to detect cracks, corrosion, or damage of the lower spar fitting body and lug, and corrective actions, if necessary. That AD also provides for optional terminating action for the repetitive inspection requirements. That AD was prompted by reports that fatigue cracking was found in the lower spar fitting lug on the number 3 pylon and in the lower spar fitting body. The actions specified by that AD are intended to detect and correct such fatigue cracking, which could result in failure of the strut and separation of the engine from the airplane. This amendment references additional service bulletins for accomplishment of the optional replacement, and clarifies that accomplishment of certain AD's terminates the repetitive inspections.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1999/01/07/99-186/airworthiness-directives-boeing-model-747-series-airplanes)
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