# Proposed AD 2000-NM-128-AD: Learjet Model 55 Series Airplanes and Model 60 Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2001-12-02
- Action: Notice of proposed rulemaking (NPRM).
- Published: March 19, 2001, 66 FR 15362
- Comments due: May 3, 2001
- Became: [AD 2001-12-02](https://openairdocs.org/ad/2001-12-02)
- Docket: 2000-NM-128-AD
- FR document: 01-6646
- Official PDF: https://openairdocs.org/files/sha256/eb/af/ebaf6a4cbe3ae2bbb904632753d170fe944367edc0bcaf5e081e7b3ded07b59e (from https://www.govinfo.gov/content/pkg/FR-2001-03-19/pdf/01-6646.pdf)
- Federal Register: https://www.federalregister.gov/documents/2001/03/19/01-6646/airworthiness-directives-learjet-model-55-series-airplanes-and-model-60-airplanes
- Page: https://openairdocs.org/proposed/2000-NM-128-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Learjet Model 55 Series Airplanes and Model 60 Airplanes. This proposal would require replacement of the brake valve adjustment screw with a new improved screw, and for certain airplanes, it would also require installation of a new brake valve lever stop. This action is necessary to prevent bottoming of the valve components before contact of the brake valve lever with the stop, which could result in loss of all hydraulic fluid and consequent loss of normal braking. This action is intended to address the identified unsafe condition.

## Notices in this docket

- Mar 19, 2001: Notice of proposed rulemaking (NPRM). (first notice), FR document 01-6646, comments due May 3, 2001 (https://www.federalregister.gov/documents/2001/03/19/01-6646/airworthiness-directives-learjet-model-55-series-airplanes-and-model-60-airplanes)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.