Maintenance and repair involving the removal and refit of the
variable stator vane levelling arm pins to the Pratt & Whitney
PW4000 engine. This procedure involves the flaring of the pins for
retaining in the synchronising ring backed up by a service bulletin
edict to tack weld the pins to the ring. These procedures appear
not to be successful in accomplishing the desired retention of the
pins.
Refer to
BO/200400726 for details.
Safety Recommendation
The Australian Transport Safety Bureau recommends that the US
Federal Aviation Administration review Pratt & Whitney PW4000
engine maintenance procedures for ensuring the integrity of high
pressure compressor variable stator vane synchronizing ring pins,
to ensure that they adequately address and manage the potential for
loss of vane arm pin retention.
