The FAA issued an emergency airworthiness directive (AD) on January 8 that requires preflight engine test runs and inspections of certain commercial airlines and business jets when the oil temperature is below freezing (32 degrees F). If tests are not performed successfully, the affected aircraft are prohibited from further flight.
Today’s order—designed to prevent in-flight engine shutdown owing to loss of engine oil—affects 120 U.S. aircraft equipped with Allison 3007A and 30007C engines. The aircraft affected are Embraer 145s and Cessna 750 series aircraft. Principal commercial airlines affected are Continental Express, American Eagle, and Trans States, all of whom operate the Embraer 145. The Cessna 750 is a corporate jet.
The FAA received three reports this week of in-flight engine shutdowns involving Allison Model AE 3007A and AE3007C series turbofan engines. The agency has found that starting these engines in very cold temperatures (below 32 degrees Fahrenheit) can cause the starter shaft o-ring seal to allow oil to leak from the engine’s accessory gearbox.
Effective immediately, the AD requires operators to perform engine checks when oil temperature has dropped below 32 degrees Fahrenheit. Embraer operators must do a high-power leak check prior to flight on each of the two engines by running the engine for at least three minutes at takeoff and checking for oil leaks. Oil leaks cannot exceed two-tenths of a quart per engine per hour or the aircraft is prohibited from further flight. Cessna operators are required to operate the engine at maximum continuous power for 10 minutes and monitor the oil levels. If the oil level decreases more than a quart, maintenance is required before further flight.
This AD is considered an interim action, and as further investigation continues, additional rulemaking may be necessary.
January 11, 1999