# Proposed AD 99-NM-05-AD: McDonnell Douglas Model DC-9-80 Series Airplanes and Model MD-88 Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-24-04
- Action: Notice of proposed rulemaking (NPRM).
- Published: February 22, 1999, 64 FR 8530
- Comments due: April 8, 1999
- Became: [AD 99-24-04](https://openairdocs.org/ad/99-24-04)
- Docket: 99-NM-05-AD
- FR document: 99-4216
- Official PDF: https://openairdocs.org/files/sha256/f4/62/f4624e81dab2fe2f0518951bbed8b0ae79f318f8ab99101409807e5ab5a204ed (from https://www.govinfo.gov/content/pkg/FR-1999-02-22/pdf/99-4216.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/02/22/99-4216/airworthiness-directives-mcdonnell-douglas-model-dc-9-80-series-airplanes-and-model-md-88-airplanes
- Page: https://openairdocs.org/proposed/99-NM-05-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes. This proposal would require a one-time visual inspection to determine whether self-aligning nuts are installed at certain locations of the aft pressure bulkhead tee; and corrective actions, if necessary. This proposal is prompted by reports of failures of certain Hi-Lok pin fasteners of the aft pressure bulkhead tee due to installation of non-self-aligning nuts. The actions specified by the proposed AD are intended to prevent failure of certain Hi-Lok pin fasteners and subsequent gouging of the aft pressure bulkhead tee, which could result in fatigue cracking and reduced structural integrity of the airplane.

## Notices in this docket

- Feb 22, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-4216, comments due Apr 8, 1999 (https://www.federalregister.gov/documents/1999/02/22/99-4216/airworthiness-directives-mcdonnell-douglas-model-dc-9-80-series-airplanes-and-model-md-88-airplanes)

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