# Proposed AD 99-NM-125-AD: Boeing Model 757 Series Airplanes Equipped With Rolls Royce Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-24-07
- Action: Notice of proposed rulemaking (NPRM).
- Published: August 20, 1999, 64 FR 45483
- Comments due: October 4, 1999
- Became: [AD 99-24-07](https://openairdocs.org/ad/99-24-07)
- Docket: 99-NM-125-AD
- FR document: 99-21685
- Official PDF: https://openairdocs.org/files/sha256/36/91/36913cf420688e12e81ce428bf9e6529c230a84d1fd92e1f02e0b0d4a77af2c6 (from https://www.govinfo.gov/content/pkg/FR-1999-08-20/pdf/99-21685.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/08/20/99-21685/airworthiness-directives-boeing-model-757-series-airplanes-equipped-with-rolls-royce-engines
- Page: https://openairdocs.org/proposed/99-NM-125-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 757 series airplanes. This proposal would require modification of the nacelle strut and wing structure of certain Boeing Model 757 series airplanes equipped with Rolls Royce RB211 engines. This proposal is prompted by reports indicating that the actual operational loads applied to the nacelle are higher than the analytical loads that were used during the initial design. Such an increase in loading can lead to fatigue cracking in primary strut structure prior to an airplane's reaching its design service objective. The actions specified by the proposed AD are intended to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut.

## Notices in this docket

- Aug 20, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-21685, comments due Oct 4, 1999 (https://www.federalregister.gov/documents/1999/08/20/99-21685/airworthiness-directives-boeing-model-757-series-airplanes-equipped-with-rolls-royce-engines)

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