# Proposed AD FAA-2009-0247: Hamilton Sundstrand Power Systems T- 62T-46C12 Auxiliary Power Units

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2009-21-03
- Products: Hamilton Sundstrand
- Product type: Appliance
- Action: Notice of proposed rulemaking (NPRM).
- Published: April 13, 2009, 74 FR 16811
- Comments due: June 12, 2009
- Became: [AD 2009-21-03](https://openairdocs.org/ad/2009-21-03)
- Docket: FAA-2009-0247 (https://www.regulations.gov/docket/FAA-2009-0247, where comments are filed)
- Project: 2009-NE-07-AD
- FR document: E9-8311
- Official PDF: https://openairdocs.org/files/sha256/69/53/6953eb8302878a20c09a273171e30b0e4458e16035cb05e4b1fe5b228831365e (from https://www.govinfo.gov/content/pkg/FR-2009-04-13/pdf/E9-8311.pdf)
- Federal Register: https://www.federalregister.gov/documents/2009/04/13/E9-8311/airworthiness-directives-hamilton-sundstrand-power-systems-t-62t-46c12-auxiliary-power-units
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/F0E547FE05831B0F862575970052B450.0001
- Page: https://openairdocs.org/proposed/FAA-2009-0247

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for Hamilton Sundstrand Power Systems T-62T-46C12 auxiliary power units (APUs). This proposed AD would require upgrading the software in the APU full-authority digital controller (FADEC), from software version 02.01.000 to version 03.00.000. This proposed AD results from two reports of APU compartment explosions due to over-fueling of the APU at low rpm during the start sequence. We are proposing this AD to prevent over-fueling of the APU during the start sequence, which could lead to fuel explosions, injury, and damage to the APU and the airplane.

## Notices in this docket

- Apr 13, 2009: Notice of proposed rulemaking (NPRM). (first notice), FR document E9-8311, comments due Jun 12, 2009 (https://www.federalregister.gov/documents/2009/04/13/E9-8311/airworthiness-directives-hamilton-sundstrand-power-systems-t-62t-46c12-auxiliary-power-units)

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