US OPERATORS of Pratt & Whitney-powered Boeing 757s are being required to perform engine run-ups in cold weather to remove ice which may form in the compressor.
The US Federal Aviation Administration has issued an emergency airworthiness-directive (AD) following incidents in which ice broke loose from low-pressure-compressor stators at full take-off power and caused damage to high-pressure-compressor blades.
According to the US engine manufacturer, the requirement to run the engine up to more than 50% power during ground operations in cold weather has been in the operating manual since the PW2000 entered service in 1983.
Following five incidents of ice-caused compressor damage during the severe US winter of 1993, the manufacturer reminded operators of the procedure.
Now, the FAA has issued the AD to give the requirement "the force of law" as US airlines gear up for winter operations, the company says.
The AD reminds operators that the engine anti-ice system only protects the inlet cowl and cannot prevent or remove ice accumulation on the stator stage just behind the fan.
The directive requires that engine run-ups be based on air temperature and visible moisture, rather than indications of icing on the airframe.
The FAA has advised crews to look for ice build-up on the stator and remove it, if necessary, before taxiing out.
Source: Flight International
