No one died on American Airlines (AA) Flight 383 after one of its engines exploded into flames, but CNBC reported that the National Transportation Safety Board (NTSB) chairman Robert Sumwalt said it “came too close for comfort,” which resulted in the board issuing recommendations for potentially similar incidents in the future.
In October 2016 pilots on the doomed flight aborted takeoff at Chicago’s O’Hare International Airport after an uncontained engine failure started a fire beneath the right wing, according to USA Today. The 161 passengers and nine crew members were safely evacuated. Later in the day the NTSB announced that the engine fire on the Boeing 767 bound for Miami was caused by a General Electric Company (GE) engine turbine disc.
The disc failed, shattered and sliced through the fuel line, hurling the fractured pieces up to half a mile away from where the plane stopped. The Chicago Tribune explained that “[t]he fire was so hot that it burned through the fuselage and the tip of the wing slumped onto the runway.”
Engine shells are designed to contain any loose parts if the engine fails. Yet, as Sumwalt explained, they can experience a rare, but extremely dangerous, uncontained engine failure, which occurred on Flight 383.
The explosion, fire and ensuing chaotic evacuation made it “one of the most serious aviation incidents in recent years,” as the Chicago Tribune described. A “cumbersome engine failure checklist slowed the cabin crew’s response to the situation. Flight attendants had trouble operating the plane’s intercom system and were unable to coordinate an evacuation with the cockpit. The flight attendants, concerned by the billowing smoke, initiated the evacuation. However, passengers were exiting the plane just behind an engine that was still running. One passenger was knocked down from the blast of the operating engine. And, flight attendants arguing with passengers determined to retrieve their carry-on bags slowed the evacuation process, putting passengers’ lives at an even greater risk.
It is those circumstances that led the NTSB to issue several recommendations including:
- Developing a separate checklist to guide the crewmembers through engine failures that occur while an aircraft is on the ground. The existing checklist applies only to engine failures and fires that occur while the aircraft is in the air.
- Enhanced training on evacuation procedures, specifically regarding the use of the fleet’s intercom phone system.
- Improving measures that prevent passengers determined to retrieve carry-on bags, which slows the evacuation process.
Additionally, investigators found a microscopic manufacturing flaw in the GE turbine disc that led to the catastrophic engine failure. The fatigue on the part was particularly exceptional since it had only flown 11,000 of its 15,000 lifetime flights limit. The board determined that the flaw would not have been seen during manufacturing or inspections between flights, USA Today reported. Therefore, it found that “additional study is needed to determine if ultrasonic inspection methods should be required both during manufacturing and subsequent inspections,” according to CNBC.
The disc was made from a common alloy called Iconel 718, but GE claimed it had not experienced a failure caused by an anomaly in the alloy in more than 30 years. Days following the incident, the company said that it had identified and was continuing to evaluate the disc’s anomaly. GE worked with other airlines to remove similar discs from service.