A test-engine failure that ended in a fire in an early version of Pratt & Whitney’s geared turbofan engine two years ago was the result of an engine seal failure after a “hot shutdown” conducted during testing, the Transportation Safety Board of Canada said Tuesday.
The failure of an engine oil feed tube seal led to a turbine rotor failure and a subsequent fire during ground tests at the Montreal International Airport in Mirabel, Quebec, the agency said.
East Hartford-based Pratt subsequently produced an “enhanced seal” and worked out a revised cool-down procedure, and other measures “to monitor engine temperatures and prevent hot shutdowns,” the agency said.
The May 2014 engine failure involved a PW1500G geared turbofan engine on a twin-engine Bombardier CS100 aircraft.
An onboard crew was conducting engine tests when the left engine had an “uncontained turbine rotor failure and sudden power loss,” the agency reported.
The crew immediately shut down the engine and declared an emergency, the report added.
The two pilots and four test engineers on the plane evacuated the aircraft safely, but the engine and aircraft received substantial damage, the report said.
The investigation also found that Pratt had issued a restriction and special instructions dealing with cooling procedures for the engines before shutdown, which appeared to have been misinterpreted, the report said.
The agency also said Pratt’s newer engines feature an enhanced oil-supply tube and a cooling airflow configuration that separate the turbine rotor airflow from the bearing compartment to prevent similar fires.
Following the 2014 fire, Bombardier grounded the CSeries test aircraft fleet until the cause could be clearly established, the agency added.
The issue was resolved to the point that Bombardier and Pratt this year have received major orders for the planes, including an April contract for up to 125 aircraft from Delta Air Lines.
The total contract, including options, could be worth more than $2 billion to Pratt, minus financial incentives.
Pratt’s geared turbofan engine program also experienced a series of setbacks over the past year on Airbus Industrie’s A320neo planes. Longer-than-usual engine startup times and other issues delayed deliveries of the planes, as Pratt sought to retrofit the engines with new software to shorten the engine startup process.
Pratt spokesman Ray Hernandez said Wednesday that his company has been working closely with Bombardier to assure the continuation of successful flight-testing.
Transport Canada certified the aircraft on Dec. 18, 2015, Hernandez said. Both the European and U.S aviation authorities certified the aircraft on June 15, he said.
“It is important to note the fan drive gear system was not involved in the incident,” Hernandez said of the core feature of the new engines. “We are confident in the safety and efficacy of our engine,” he added.
