曝光台 注意防骗
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had already started, indicating a certain carelessness in the realization of the prescribed working
procedures.
In the morning shift on 19 March 2001 an aircraft electronic technician holding a B2 qualification
was to replace the plug segment AE according to the “ONE by ONE” method with the assistance of
an aircraft electronic technician B1. During this action it was determined that the new segment (AE)
was incompatible with the three remaining segments of the plug. The possibility to find a fitting plug
segment within an adequate period of time would generally have been an alternative, but for internal
reasons another decision was made. If only the segment AE would have had to be replaced
BFU German Federal Bureau of Aircraft Accidents Investigation
5X004-0/01 23
only the pair of wires 0603 of the monitor channel could have been interchanged on this segment,
the pair of wires 0597 of the Command Channel on the segment AA would have remained untouched
and with a high probabiltiy an error message would have appeared on the display of the
electronic centralized aircraft monitoring system (ECAM).
The reconnection of more than 420 pins of the whole plug was connected to a high risk of errors.
Thus it would have been necessary to measure each individual wire (continuity check) as required
by the manufacturer’s instruction AMM 20-52-10 for major actions on the control system. In reply to
the enquiry of the mechanics to staff members of the Maintenance Support Department, whether
each individual wire should be measured, this action was orally cancelled with reference to the
SPM of the organisation. The reason stated for this decision was the technical experience from
practice that the functional test to be performed after completion of the work would reveal wiring
errors. Erroneously the SPM of the organisation left this decision to the discretion of the staff
members of the Maintenance Support. Following the occurrence this condition was immediately
corrected.
In the Standard Practices Manual the procedure which would have had to be applied in this case is
unambiguously established. This provision could have been cancelled only in writing in the form of
an engineering order. In the opinion of the BFU the omission of the continuity check was not allowable
with regard to the severity of the actions on the control system.
It was also inadmissible to perform the functional check and the control system check simultaneously,
they would have had to be carried out independently of each other. The person who had
conducted the double inspection and thus was the last to have the chance to find the interchanged
connection had not been informed sufficiently about the previous work flow. Presumably it was not
BFU German Federal Bureau of Aircraft Accidents Investigation
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known to him that the staff members of the late shift had by direction of the Maintenance Support
not measured the reconnected wires, as actually required.
As a further omission, the control system test and the functional test were made only from the righthand
sidestick and not from both sidesticks and a comparing visual check of the control surfaces of
the aeroplane was waived completely.
The fact that the manufacturer's instruction in the AMM 27-93-00-710-050 (-Push the FLT CTL
ELAC 1 (2) push button switch - Move the side-stick around in its two axis from stop to
stop.) was not unambiguous, was the reason why the test was conducted only from the right-hand
sidestick. The a.m. instruction of the manufacturer had meanwhile been changed at the suggestion
of the maintenance organisation and now requires mandatory tests from both sidesticks.
The question of the BFU staff members why the tests had been conducted from the right-hand
sidestick which was not concerned was answered with the statement that it did not matter which
sidestick was used. As both ELACs were connected to each other possible faults of the one or the
other ELAC would surely be indicated. This statement indicates lacking system knowledge of the
mechanics.
Severe errors in the conduct of the first check and cross-checks arose. Presumably the aircraft
mechanics involved who carried out the checks underestimated the significance of the previous
action. There is no other explanation for the fact that the cross checking staff member had conducted
the required cross-check using the working documents which where aboard the aircraft and
had already been used by the staff member having conducted the first check, although according
to the regulations he would have had to use his own impartial documents. Obviously the imporBFU
German Federal Bureau of Aircraft Accidents Investigation
5X004-0/01 25
tance of the cross-check to this repair had not been realized. In this case not the workflow but the
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