AWB 24-2 Issue 1 - Aircraft Alternator Alert
AWB 24-2 Issue 1, 17 August 2001
Aircraft Alternator Alert
Electrosystems Alternators P/N2366 Prestolite P/N ALV9510R
The purpose of this bulletin is to draw the attention of aircraft owners and maintainers to a problem encountered with ALV9510R alternators.
The Major Defect Reporting (MDR) system has alerted CASA to the failures of the ALV9510R alternators, which have been sourced by Australian distributors from Electrosystems Inc (USA) within the last 15 months. A significant proportion of these alternators have failed.
The consequence of this problem is the short time in service (TIS) of the alternators and instances of metal contamination of engines following alternator and associated drive train failure have been reported. These engines have required strip downs.
The failure of these alternators appears to be due to rear bearing collapse or rotor shaft failure. In some instances reported indications are of the rotor shaft slipping in the rear bearing. Reports indicate that if the fault is not detected it can progress to where the alternator starts shedding parts of components such as bearings with consequential damage to the alternator drive train and resultant engine metal contamination.
These alternators are failing with TIS of under 200 hours and one as low as 6 hours.
Because it is not yet clear what is causing the failures, CASA is investigating this problem.
CASA recommends that these alternators be inspected at the earliest opportunity
- for signs of shaft/bearing slippage in the rear housing
- for trace of wear on the rotor shaft or the rear bearing
- damage to the slipring and drive end housings.
In addition the procedure as outlined in AD/ELECT/28 Amt3 should be followed with these alternators. Your attention is also drawn to AAC 6-64.
Consideration should be given to checking the balance of the rotor and checking for cracks on both the slipring and drive end housings.
All reports of damage and failure should be forwarded to CASA using the MDR system as soon as any anomaly is discovered to assist CASA with its investigation.
When CASA obtains further information on this problem it will be made available as an supplementary issue of this AWB.