Engineering news
The engine problem which has prevented the appearance of the F-35 at the Farnborough International Airshow this week is an isolated malfunction that will only cause minor delays to the programme, US officials have reassured.
Speaking today at the airshow in Hampshire, US undersecretary for defence, Frank Kendall, said that there is a growing body of evidence to suggest that the problem is not systemic and will only cause “minor problems” to the programme.
He said: “We are sorting through the root cause of the accident. Engineers are accessing the data before we put the aircraft back in the air. It's an ongoing, intensive process. Hopefully they will be able to reach a conclusion and put it back in the air soon.”
One of the Pratt and Whitney (P&W) engines on a Joint Strike Fighter caught fire and broke apart while preparing to take off from a Florida air base on 23 June. This has caused the entire fleet of F-35s to be grounded while all 98 engines in service are checked.
The P&W engines use a three-stage fan that uses integrally bladed rotors (IBR) made of titanium. Lieutenant General Chris Boghdan, programme executive officer for F-35 form the US Air Force, said that the problem was caused by “severe” rubbing of the fan blades against the stator in the third stage IBR at the front of the engine. The rubbing created a a higher temperature, which resulted in “microcracking” and resulted in high temperature fatigue.
Boghdan said: “None of the 98 engines checked indicated the same phenomenon as on the one that failed. We know what happened, we are now trying to figure out why it happened and what the potential mitigations may be.
“The timing was bad and we're all disappointed, it would have been a wonderful thing for everyone could to see its not a paper aeroplane and is a technical marvel. But we haven't given up yet on getting here this week.”
Boghdan added that the problem was unrelated to any previous faults in the engine and that he expected the issue to have minimal impact on the F-35 project's progress.
The fifth generation fighter aircraft was also supposed to appear at the naming ceremony of the HMS Queen Elizabeth aircraft carrier and the Royal International Air Tattoo earlier this month.
The F-35 is the US' most expensive defence project ever at about £230 billion. Some 500 UK companies are involved in the project and the UK's initial order is for F-35s. However, the project has received heavy criticism for cost increases and delays. The aircraft is now expected to enter service for the US Marines in 2015, five years later than planned.