# Proposed AD FAA-2009-0868: ZLT Zeppelin Luftschifftechnik GmbH & Co KG Model LZ N07-100 Airships

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2009-25-03
- Products: ZLT Zeppelin Luftschiffechnik
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: September 21, 2009, 74 FR 48019
- Comments due: November 5, 2009
- Became: [AD 2009-25-03](https://openairdocs.org/ad/2009-25-03)
- Docket: FAA-2009-0868 (https://www.regulations.gov/docket/FAA-2009-0868, where comments are filed)
- Project: 2009-CE-047-AD
- FR document: E9-22641
- Official PDF: https://openairdocs.org/files/sha256/f4/81/f4818f221a816aeff9cdf8a3676369486931027d7163ca0e5d3fc83203efeb73 (from https://www.govinfo.gov/content/pkg/FR-2009-09-21/pdf/E9-22641.pdf)
- Federal Register: https://www.federalregister.gov/documents/2009/09/21/E9-22641/airworthiness-directives-zlt-zeppelin-luftschifftechnik-gmbh-and-co-kg-model-lz-n07-100-airships
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/5CDA5F065B4F7B1986257638005B557E.0001
- Page: https://openairdocs.org/proposed/FAA-2009-0868

## Summary

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: The manufacturer has advised of receiving a report that during start up on ground a RH propeller gear box (PGB) on the airship has failed resulting in free rotation of the propeller. Investigation performed by the manufacturer revealed that the bevel gear in the propeller gearbox had cracked near the hub area. During an extensive metallurgical investigation of the cracked bevel gear some different manufacturing deviations outside of the specifications were detected. Deviations in the heat treatment, wall thickness of the bevel gear near the hub area, and score marks caused during the production process have been established as causal factors forthis failure. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

## Notices in this docket

- Sep 21, 2009: Notice of proposed rulemaking (NPRM). (first notice), FR document E9-22641, comments due Nov 5, 2009 (https://www.federalregister.gov/documents/2009/09/21/E9-22641/airworthiness-directives-zlt-zeppelin-luftschifftechnik-gmbh-and-co-kg-model-lz-n07-100-airships)

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