# Proposed AD 99-CE-20-AD: Pilatus Aircraft Ltd. Models PC-12 and PC-12/45 Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-17-01
- Action: Notice of proposed rulemaking (NPRM).
- Published: June 14, 1999, 64 FR 31756
- Comments due: July 14, 1999
- Became: [AD 99-17-01](https://openairdocs.org/ad/99-17-01)
- Docket: 99-CE-20-AD
- FR document: 99-14937
- Official PDF: https://openairdocs.org/files/sha256/1b/dc/1bdc71b736ca3c7835de9e983d30be9f53ff72689bb0dfa6a2ae194b35fb8777 (from https://www.govinfo.gov/content/pkg/FR-1999-06-14/pdf/99-14937.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/06/14/99-14937/airworthiness-directives-pilatus-aircraft-ltd-models-pc-12-and-pc-1245-airplanes
- Page: https://openairdocs.org/proposed/99-CE-20-AD

## Summary

This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes. The proposed AD would require replacing all flap drive shafts with flap drive shafts of improved design, installing additional gaskets on the power drive unit, and modifying the attachment and supporting hardware. The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by the proposed AD are intended to prevent the flap drive shafts from corroding to the point where the flexible shafts in the flap drive system rupture, which could result in the inability to utilize the flap system with reduced airplane control.

## Notices in this docket

- Jun 14, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-14937, comments due Jul 14, 1999 (https://www.federalregister.gov/documents/1999/06/14/99-14937/airworthiness-directives-pilatus-aircraft-ltd-models-pc-12-and-pc-1245-airplanes)

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