An Excellent COS/SMS Case Study by Steve Szpunar, MARPA Safety Committee Chairman
On February 20, 2021, United Airlines Flight 328 from Denver to Honolulu suffered a fan blade out (FBO) event during the climb to cruise altitude. The aircraft was a Boeing 777-222 fitted with Pratt and Whitney PW4077 engines. A photo taken by a passenger of the damaged number two engine is shown below.
Inlet and fan cowling debris from the aircraft and engine also fell down upon the city of Broomfield, Colorado and the surrounding area. Fortunately, no one on the ground was injured.
Although the engine suffered significant damage, the United flight crew returned to the airport and performed a safe engine out landing.
The failed P&W fan blade fractured near the hub due to low cycle fatigue, and then impacted the trailing blade, resulting in secondary damage to it.
The blade was “contained” per 14 CFR §33.19, as none of the high energy fan blade debris penetrated the fan containment case, which is comprised of metal construction surrounded by Kevlar® fabric belts.
However, the fact that the inlet and fan cowls (certified under 14 CFR §25.362 Engine Failure Loads) were liberated is not acceptable; the release of these items could potentially hazard the aircraft by impacting the fuselage or empennage. To wit, a CFM56-7 FBO on Southwest 1380 on April 17, 2018 event resulted in similar fan cowl release which damaged the fuselage, causing explosive decompression and the unfortunate death of a passenger.
As part of my COS responsibilities at HEICO, and as Chairman of the MARPA Safety Committee, I review all aircraft incidents, AD’s, etc. However, I am especially interested in this event since during my tenure at GE Aviation, I led the GE90 123” fan rotor design team. We certified the world’s first composite, as well as GE’s first wide chord fan blade for the 777. The photo at the left is was taken after we successfully completed the medium bird ingestion certification test in September, 1995. (I am the guy kneeling with the blue shirt.) It is certainly one of the highlights of my 42 year engineering career.
Could a rigorous COS/SMS system have prevented this problem? Were there any significant precursors or risk items that could have been identified earlier?
STAY TUNED!
During the 2021 MARPA Spring Virtual Event this May 18-19, I will discuss my thoughts on how utilizing SMS/COS methodologies could have prevented these FBO events. Register online today or learn more about this complimentary event on MARPA’s website !
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