Preliminary analysis finds leaks caused engine failure, forcing an aircraft to land in an Indiana street in December
Pilatus Aircraft has revealed that preliminary findings after the 14 December street landing of a PC-12 in South Bend, Indiana, indicate the engine failed because of leakage within the fuel control unit (FCU) pneumatic system.
Pilatus vice-president research and development John Senior says the Pratt & Whitney Canada PT6 engine is under examination and the manufacturer "attributes the event to leakage within the fuel control unit pneumatic system". Senior adds: "P&WC is evaluating improvements to the FCU pneumatic system that will be retrofittable to the fleet." He also points out that the PC-12 engine "is equipped with a manual override [MOR] system that enables engine power to be recovered in the event of an FCU pneumatic leakage".
Pilatus and P&WC say they are reissuing service information letters reminding all PC-12 operators of the necessary procedures for use of the MOR system, and point out: "The safety record of the PC-12 remains high with the engine in-flight shutdown rate being better than the world's most stringent rate proposed for single-engine instrument meteorological conditions [SEIMC] operations, at less than 10 per million flight hours." The US National Transportation Safety Board is continuing its investigation of the South Bend incident.
Meanwhile, the European Joint Aviation Authorities Operations Sectorial Team (OST) will consider on 13-14 April what may be the final amendments to the draft regulation that will see the JAA give its approval to commercial SEIMC operations in Europe.
At that meeting the SEIMC working group will not be studying any requirements in addition to the long list of those already proposed and technically approved - the remaining issue has been the wording of the existing proposed regulations and requirements, according to sources close to the JAA. If the OST approves the working group's proposed wording revisions, the draft regulation will go forward to the JAA Committee for approval at its June meeting. This would be the last time the rule could be considered by the JAA before the European Aviation Safety Agency takes over the operations regulatory remit from the JAA in October.
The national aviation authorities opposed to SEIMC - Germany, the Netherlands, Italy and the UK - do not claim to do so on purist safety grounds, as they concede that certain PT6-engined singles have better safety records than the piston-powered twins certificated for commercial IMC operations. They are concerned, says aircraft dealer Bob Crowe, at being held accountable for any future accident in which someone is killed by an aircraft operating under SEIMC rules.
DAVID LEARMOUNT / LONDON
Source: Flight International
