The crash of USAir Flight 427 killed all 132 aboard and became the second-longest air crash investigation in history, ultimately revealing a fatal rudder design flaw in the Boeing 737.
Key Facts
- Date
- September 8, 1994
- Aircraft type
- Boeing 737-3B7
- Total fatalities
- 132 people
- Investigation ranking
- Second longest air crash investigation in history
- Determined cause
- Rudder hard-over due to frozen dual servo valve
- Departure / destination
- Chicago O'Hare to Palm Beach via Pittsburgh
By the Numbers
Location
Cause → Event → Consequence
Hot hydraulic fluid entered the rudder's dual servo valve, causing it to freeze and reverse its function. When the crew commanded a rudder correction on approach to Pittsburgh, the rudder deflected hard over in the opposite direction, a condition the pilots could not have anticipated or countered in time.
On September 8, 1994, USAir Flight 427, a Boeing 737-3B7 en route from Chicago to Palm Beach with a stopover at Pittsburgh, crashed in Hopewell Township, Pennsylvania, while on approach to Runway 28R. The aircraft entered an aerodynamic stall from which Captain Peter Germano and First Officer Charles B. Emmet III were unable to recover.
All 132 people aboard were killed, making it the deadliest air disaster in Pennsylvania history. The ensuing NTSB investigation, one of the longest in aviation history, identified the Boeing 737 rudder servo valve as the root cause and also resolved the earlier unsolved crash of United Airlines Flight 585, prompting significant design and regulatory changes to the 737 fleet.