Originally Posted by NTSB
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Examination of maintenance records indicated that both main landing gear units were replaced on the incident airplane in early February 2008.
Originally Posted by AMM
TASK 32-42-00-720-002-A
Functional test of the tachometers
1. Reason for the Job
The test below is to do the check of the tachometer for correct operation after a replacement of one of them.
NOTE : If the MLG WHEEL TACHYMETER DRIVING TOOL is not available, as an alternative you can use:
- two standard drilling machines with the DRIVING ADAPTOR (98D32403004000).
NOTE : You must do this test if there is a risk of wiring cross connection between two tachometers (replacement of the MLG or of the electrical
harness of the MLG).
If only one tachometer is replaced or disconnected, THIS TEST IS NOT MANDATORY as the BSCU will do the automatic check of the tachometer.The BSCU will do this check during aircraft roll between 10 m/s and 40 m/s (32.81 ft/s and 131.23 ft/s) to make sure that the tachometer operates correctly.
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So it looks like UNITED did not do their job correct
