FAA targets PW4000 sensor flaw linked to tailpipe fires, in-flight shutdowns

An FAA proposed order comes after P&W issued service bulletins to address the concern.

The Federal Aviation Administration has responded to a sensor durability problem that has caused multiple incidents of Pratt & Whitney (P&W) PW4000 turbofans suffering tailpipe fires and in-flight shutdowns.

The agency issued a proposed airworthiness directive (AD) that would require airlines to replace pressure burner sensors on several PW4000 variants powering 210 US-registered jets.

Boeing 747-400s, 767s and MD-11 Freighters have PW4000 variants targeted by the regulator’s action.

“This proposed AD was prompted by multiple reports of tailpipe fire, loss of thrust control and engine in-flight shutdown due to undetected deterioration of pressure burner sensors,” says the FAA’s proposal, released on 22 May.

The regulator does not reveal details about the incidents.

The deterioration can cause erroneous sensor readings that result in “incorrect fuel commands”, the FAA adds, noting that the sensors are housed within electronic engine control modules.

The proposed rule would require operators to replace or repair the sensors every 30,000 flight hours or 10 years in service. Sensors that have already exceeded those limits would need to be repaired or replaced within periods ranging between 10-30 months.

The FAA is accepting public comments about its proposal for 45 days.

“This [proposed rule] is consistent with a previously issued service bulletin to operators and requires the overhaul of an externally mounted component. Compliance will not require engine removal,” P&W says.

Story updated on 22 May to include a new comment from P&W and to remove a prior comment P&W said had been inaccurate.