CH149901
Cormorant
28
Oct 2002
CFB Comox, BC
While conducting a 6-month check on CH149901, the technician
found 2 bolts and 1 nut lying in the forward compartment
of the flexible coupling for the #1 section of the tail
rotor driveshaft. Further investigation revealed that
the flexible coupling was missing 2 bolts and 2 nuts.
It was also noted that the remaining 4 securing bolts
and nuts were backed off. The aircraft was quarantined
and the Deputy Site Manager was alerted. An extensive
FOD check produced 2 bolts and 1 nut. The remaining
nut is believed to have exited the aircraft during flight.
CH149901 had flown for approximately 73 hours since
the last maintenance activity on this section of the
tail rotor drive shaft, which was documented in the
support work for the Main Gear Box (MGB) support work.
Though accident potential was very high, there was no
damage to the aircraft.
The investigation indicates that the personnel involved
with the last maintenance action on the Tail Rotor Drive
Shaft removal and installation on CH149901 were interrupted
and did not follow approved maintenance procedures.
One month prior to completion of the MGB change, two
qualified technicians attempted to install the Tail
Rotor Drive Shaft on CH149901. These technicians had
to stop work due to the lack of a special adaptor to
be used with the torque wrench. The Tail Rotor Drive
Shaft was left installed in place with the flexible
couplings at both ends fixed with hand tight bolts.
A request was filled out to have the adaptor locally
manufactured. No entry was made to document the state
of the Tail Rotor Drive Shaft as well as any work signed
as being completed in maintenance records. When the
adapter was available, a different technician carried
out the Tail Rotor Drive Shaft installation and signed
the Independent Check, contrary to the IMP Maintenance
Process Manual. Furthermore the work order that documented
the Tail Rotor Drive shaft installation was inaccurate.
The Maintenance Release Authority (MRA) did not notice
the inaccuracy and did not ensure that the technician,
initially involved with the rectification of the unserviceability,
was not involved in the independent check.
Preventative measures taken to date include a maintenance
alert distributed to all CH149 maintenance organisations
showing pictures of the occurrence and provided some
contributing factors. It noted how close this incident
came to being a disaster and reminded technicians that
their professionalism is the last and most critical
line of defence.
In an effort to re-establish confidence in the airworthiness
of the aircraft, a detailed verification was initiated
on 14 Nov 02. Aircraft CH149904 and CH149906 were taken
out of service for a nose to tail visual inspection,
carried out together by techs and Flight Engineers,
focusing on all flight critical systems within the aircraft.
Furthermore, the level of supervision for major maintenance
activities was increased at Comox Main Operating Base
(MOB).
The Director General Aerospace Equipment Program Management
(DGAEPM), in consultation with the Commander of the
1 Canadian Air Division (Cmd 1 CAD), convened a staff
assistance visit (SAV), comprised of representatives
from the Project Management Office - Canadian Search
& Rescue Helicopter (PMO CSH), Director of Technical
Airworthiness (DTA), IMP, and the operational community.
Recommendations from this SAV are being followed closely
by DGAEPM staff.DTA conducted an Airworthiness Surveillance
Audit of the IMP CH149 Cormorant Aircraft Maintenance
Organisation (AMO) as part of the SAV.
Future investigation will focus on CH149 Maintenance
Organisations and consider measures to ensure strict
adherence to airworthiness principles. The CH149 maintenance
program and accreditation process will also be explained.
Additionally, the actions arising from the CH-149 SAV
follow-up report will be reviewed and Flight Safety
related issues or "lessons learned" will be
promulgated.
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