AS55, vicinity Fairview Alberta Canada, 1999

Summary: 

On 28th April 1999, an AS-355 helicopter suffered an in-flight fire attributed to an electrical fault which had originated from a prior maintenance error undetected during incomplete pre-flight inspections. The aircraft carried out an immediate landing allowing evacuation before the aircraft was destroyed by an intense fire.

Event Details
When: 
28/04/1999
Event Type: 
Day/Night: 
Day
Flight Conditions: 
VMC

18660

Flight Details
Operator: 
Type of Flight: 
Public Transport (Non Revenue)
Flight Origin: 
Intended Destination: 
Take-off Commenced: 
Yes
Flight Airborne: 
Yes
Flight Completed: 
No
Phase of Flight: 
Descent
General
Tag(s): 
Inadequate Airworthiness Procedures
FIRE
Tag(s): 
Fire-Electrical origin
HF
Tag(s): 
Aircraft acceptance, Procedural non compliance
EPR
Tag(s): 
Emergency Descent, Emergency Evacuation
AW
System(s): 
Electrical Power
Contributor(s): 
Maintenance Error (valid guidance available)
Outcome
Damage or injury: 
Yes
Aircraft damage: 
Hull loss
Non-aircraft damage: 
Yes
Non-occupant Casualties: 
No
Off Airport Landing: 
Yes
Ditching: 
Yes
Causal Factor Group(s)
Group(s): 
Aircraft Technical
Safety Recommendation(s)
Group(s): 
Aircraft Operation, Aircraft Airworthiness
Investigation Type
Type: 
Independent

Description

On 28th April 1999, an AS-355 helicopter suffered an in-flight fire attributed to an electrical fault which had originated from a prior maintenance error undetected during incomplete pre-flight inspections. The aircraft carried out an immediate landing allowing evacuation before the aircraft was destroyed by an intense fire.

Summary

The following is an extract of the summary from the official TSB (Canada) Aviation Investigation Report:

"The…AS355…had completed a routine gas pipeline patrol and was returning to Fairview, Alberta… at about 800 ft above ground, the red battery temperature light illuminated on the warning panel. The pilot… turned off the battery. About three minutes later… the helicopter lost all electrical power and the cabin and cockpit began to fill with smoke and fumes. The pilot… accomplished an emergency landing at once on a …field… both occupants evacuated the helicopter without further incident or injury… the helicopter was subsequently destroyed by an intense ground fire."

The report makes the following findings:

  • "The auxiliary battery paralleling cable was not attached to the positive post of the main battery during routine maintenance.
  • The in-flight fire occurred when the unattached battery cable arced through the battery compartment forward bulkhead in flight and ignited the flammable nylon survival gear bags in the adjacent baggage compartment.
  • The proximity of the highly flammable nylon survival gear bags to the battery compartment electrical wiring represented a hazard and contributed to the initiation and propagation of the in-flight fire.
  • The battery compartment Daily Operating Checks, which may have identified the error, were not being conducted by either pilots or AMEs."

There were other findings relating to the maintenance organisation.

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Further Reading

For further information, see the full TSB Report: TSB Aviation Investigation Report A99W0061

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