# Proposed AD FAA-2007-28016: Learjet Model 31, 31A, 35, 35A (C-21A), 36, 36A, 55, 55B, and 55C Airplanes, and Model 45 Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2007-17-17
- Products: Learjet
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: April 26, 2007, 72 FR 20775
- Comments due: June 11, 2007
- Became: [AD 2007-17-17](https://openairdocs.org/ad/2007-17-17)
- Docket: FAA-2007-28016 (https://www.regulations.gov/docket/FAA-2007-28016, where comments are filed)
- Project: 2006-NM-227-AD
- FR document: E7-8001
- Official PDF: https://openairdocs.org/files/sha256/d9/a6/d9a667e2431208278c1068e12b9813a20db904bb7ca5135185702cd9cbd02da8 (from https://www.govinfo.gov/content/pkg/FR-2007-04-26/pdf/E7-8001.pdf)
- Federal Register: https://www.federalregister.gov/documents/2007/04/26/E7-8001/airworthiness-directives-learjet-model-31-31a-35-35a-c-21a-36-36a-55-55b-and-55c-airplanes-and-model
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2EEED21B12C91CDA862572C900523CC1.0001
- Page: https://openairdocs.org/proposed/FAA-2007-28016

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for certain Learjet Model 31, 31A, 35, 35A (C-21A), 36, 36A, 55, 55B, and 55C airplanes, and Model 45 airplanes. This proposed AD would require inspecting for unsealed gaps on the pylon side of the engine firewall and cleaning/sealing any unsealed gap; and, for certain airplanes, inspecting for unsealed gaps of the pylon trailing edge and cleaning/sealing any gap. This proposed AD results from a report that unsealed gaps (penetration points) of the engine firewall were discovered during production. We are proposing this AD to prevent penetration of flammable liquids or fire through the engine firewall into the engine pylon, which could lead to fire inside the airplane.

## Notices in this docket

- Apr 26, 2007: Notice of proposed rulemaking (NPRM). (first notice), FR document E7-8001, comments due Jun 11, 2007 (https://www.federalregister.gov/documents/2007/04/26/E7-8001/airworthiness-directives-learjet-model-31-31a-35-35a-c-21a-36-36a-55-55b-and-55c-airplanes-and-model)

---
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.