UK investigators trying to puzzle out what caused the main gear box on that Bond Helicopters Eurocopter Super Puma to fail catastrophically have just confirmed that the task is proving every bit as tough as you might imagine. In a second 'initial' report they say that first it's now clear that the mechanics were effectively already doing the enhanced inspections that Eurocopter and EASA have since recommended - but there still wasn't adequate warning of the impending failure. And, to compound the situation, they still can't work out what did cause it.
You can see where this is going: we now have an aircraft that is used
on inherently risky operations which has just suffered an unexplained
catastrophic failure with no immediate hope of it being explained. What
do you do? Plenty of people would say ground it, and the AAIB's report
today makes it pretty clear that they're beginning to think the same
way. Worse, they don't distinguish between the L2 Super Puma of the type
that crashed and the newer EC225 version.
What they've actually done is effectively give Eurocopter one last chance. They've made the following urgent recommendation: It is recommended that Eurocopter, with the European Aviation Safety Agency (EASA), develop and implement an inspection of the internal components of the main rotor gearbox epicyclic module for all AS332L2 and EC225LP helicopters as a matter of urgency to ensure the continued airworthiness of the main rotor gearbox. This inspection is in addition to that specified in EASA Emergency Airworthiness Directive 2009-0087-E, and should be made mandatory with immediate effect by an additional EASA Emergency Airworthiness Directive."
It's that phrase "to ensure the continued airworthiness of the main rotor gearbox" that is the kicker. For "main rotor gearbox" read "helicopter".
What they've actually done is effectively give Eurocopter one last chance. They've made the following urgent recommendation: It is recommended that Eurocopter, with the European Aviation Safety Agency (EASA), develop and implement an inspection of the internal components of the main rotor gearbox epicyclic module for all AS332L2 and EC225LP helicopters as a matter of urgency to ensure the continued airworthiness of the main rotor gearbox. This inspection is in addition to that specified in EASA Emergency Airworthiness Directive 2009-0087-E, and should be made mandatory with immediate effect by an additional EASA Emergency Airworthiness Directive."
It's that phrase "to ensure the continued airworthiness of the main rotor gearbox" that is the kicker. For "main rotor gearbox" read "helicopter".
on April 17, 2009 7:04 PM | Reply
AAIB Bulletin No: 8/2004 Ref: EW/C2003/02/06 Super Puma G-JSAR incudes a photo of a disintegrating tranfer gear in the left hand accessory module, and a photo of a previous incident G-PUMS where the gear completely disintegrated.
The report goes on to state: "The fact that the MGB and the accessory modules share the same oil system could result in potentially serious contamination problems, thereby constituting a flight safety hazard".
Sufficient, I would have thought, to ground all Super Pumas at that time.
on April 18, 2009 11:05 PM | Reply
Since torque input to the reduction gear must be proportional to the load carried by the rotor - and therefore to the AUW of the aircraft - is there any evidence that Super Puma aircraft sometimes operate with an overloaded rotor?
on April 27, 2009 3:59 PM | Reply
Our Chief Engineer, one of America's preminent fastener experts believes it's just one more example of "Faulty Fasteners" made off the expired 1965 APM-Hexseal patent. He states "these are a receipe for failure", the biggest problem is they don't tell you ahead when they're going to fail... but in all liklihood they will. Check out his latest article in American Fastener Journal, "The past, present and future of self-sealing fasteners" by Larry J. Bogatz.