Location: Bagotville, Quebec
Status: Investigation Complete
Epilogue (EPI) (pdf 433 kb)
A maintenance contractor Periodic Augmentation Team (PAT) conducted a ground run on the Bagotville ramp, to operate the hydraulic system of Hornet CF188730. The aircraft was towed outside of the hangar and the Auxiliary Power Unit (APU) was started. After less than two minutes of operation, one of the technicians outside the cockpit observed smoke from the APU area, and requested an emergency shut-down. The technician in the cockpit had heard a voice alert for bleed air, and decided that he would shutdown if he heard it again. Coincident with the discovery of smoke, the groundrun operator heard the voice alert for the second time and immediately shut-down the APU, before the aircraft engines were started.
The heat from the APU caused serious damage to the surrounding structure, consistent with C Category Ground Accident.
The investigation revealed that the run-up was being carried-out to lower the leading edge flaps in order to make a repair. Consideration by the PAT was given to using the hydraulic cart to pressurize the hydraulic system. Based on the assumption that a run-up takes about the same amount of time as using a hydraulic maintenance stand, this option was discarded in favour of the run-up. Although time is a factor, an assessment of the risk associated with each option available was not considered. This is part of the basic concepts of Human Performance in Military Aviation (HPMA) which recommends the use of the “AIPA” model. AIPA is a closed loop process that represents the decision making model: Awareness, Implications, Plan, and Act. At the second step, Implication, the individual going through the process will assess all possible choices and their associated risk. In the case of this accident, time was the only factor considered but the reality is that there is much less risk on the equipment and personnel when using a hydraulic test stand.
The investigation also revealed that although the written emergency procedure covers this scenario properly, the ground run simulator did not have this particular scenario in their library.
As a result of this investigation, the following preventive measures were taken or recommended:
- A status board was added in the maintenance bay to clearly show if the aircraft is safe for various maintenance tasks: A/C safeties, Flight control, Landing Gear cycles, Environmental Control System (ECS), Electrical power, and Run-up. Only the floor supervisor can change the status to "green".
- Provide HPMA training to contractors working at the wing
- As a proactive measure, the team will make a review of operations/safety after every periodic.
- New scenarios will be developped for the simulator, to include emergencies while the APU is running on its own.