# Proposed AD 97-NM-21-AD: McDonnell Douglas Model DC-9 and DC-9- 80 Series Airplanes, Model MD-88 Airplanes, and C-9 (Military) Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 98-24-33
- Action: Notice of proposed rulemaking (NPRM).
- Published: March 24, 1998, 63 FR 14047
- Comments due: May 8, 1998
- Became: [AD 98-24-33](https://openairdocs.org/ad/98-24-33)
- Docket: 97-NM-21-AD
- FR document: 98-7524
- Official PDF: https://openairdocs.org/files/sha256/06/b7/06b7b5813f3ecec2eb2a9756340a109c5c5561b92e2d46bdff283cfc860e9a68 (from https://www.govinfo.gov/content/pkg/FR-1998-03-24/pdf/98-7524.pdf)
- Federal Register: https://www.federalregister.gov/documents/1998/03/24/98-7524/airworthiness-directives-mcdonnell-douglas-model-dc-9-and-dc-9--80-series-airplanes-model-md-88
- Page: https://openairdocs.org/proposed/97-NM-21-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9 and DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) series airplanes. This proposal would require a one-time visual inspection to detect fatigue cracking of the lower left nose of certain longerons and the attaching frames; repair, if necessary; and installation of a preventive modification. The proposal also would require installation of a preventive modification. This proposal is prompted by several reports of fatigue cracking of certain longerons and the attaching frames. The actions specified by the proposed AD are intended to prevent such fatigue cracking, which could result in reduced structural integrity of the fuselage, and consequent loss of pressurization of the airplane.

## Notices in this docket

- Mar 24, 1998: Notice of proposed rulemaking (NPRM). (first notice), FR document 98-7524, comments due May 8, 1998 (https://www.federalregister.gov/documents/1998/03/24/98-7524/airworthiness-directives-mcdonnell-douglas-model-dc-9-and-dc-9--80-series-airplanes-model-md-88)

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