AD/THIELERT/1 Amdt 1: Engine Failure Due to Electrical System Failure

Applicability: All TAE125-01 aircraft engines.

Requirement: 1. If not previously accomplished in accordance with the original issue of this Directive modify the electrical power supply system by accomplishing one of the following three modifications in accordance with relevant aircraft manufacturer or supplemental type certificate holder documentation (Thielert Aircraft Engine GmbH Service Bulletin TM TAE 125-008 Revision 1 also refers):

a. Replace alternator part number (P/N) 02-7150-55002R2 with alternator P/N 02-7150-55002R3.
b. Replace alternator P/N 02-7150-55002R2 with alternator and alternator regulator as follows:
(i) For Diamond aircraft installations - Alternator P/N 02-7150-55008R1 with Alternator Regulator ALT REG.
(ii) For all other installations - Alternator P/N 02-7150-55800R1 with Alternator Regulator ALT REG.
c. Install a stabilising capacitor.

2. Check the actual capacity of the aircraft battery in accordance with Gill Aircraft Battery Service Manual (Gill Document Number Q01-1120) Chapter 7.7 - continued airworthiness determination for Gill aircraft batteries.

Note: LBA AD D-2004-457R1 (EASA approval 2005-244) refers.

Compliance: For Requirement 1 - At the next 300 hourly inspection, but no later than 30 April 2005.

For Requirement 2 - At each 100 hourly inspection until Requirement 1 is accomplished.
This Amendment becomes effective on 19 January 2005.

Background: The German Luftfhart-Bundesamt has advised that during tests of the electrical system conducted by the engine manufacturer it was found that in case of a failure of the battery line, of the battery relay or of the battery the engine may fail. It was established that the reason for this failure was an electrical malfunction of the alternator.

The actions specified in the original issue of this Directive were intended to prevent an in-flight engine failure in case of a failure of the electrical aircraft power supply, which could result in an emergency landing or loss of power of the aircraft. This amendment, whilst reflecting the requirements of the original issue, extends the compliance time and introduces a repetitive battery capacity check until modifications are accomplished. The amendment also introduces minor formatting changes The original issue of this Directive became effective on 23 December 2004.

FMI: http://casa.gov.au/avreg/aircraft/ad/ADfiles/PISTON/THIELERT/THIELERT-001.pdf