Narrative:
USAir Flight 224 departed Philadelphia on a scheduled flight to Boston. While climbing through 4000 feet, the aircraft yawed and rolled to the right. Simultaneously, the crew noticed the no. 2 throttle slam and lock to the idle position. A continuous airframe buffet began. Soon thereafter, the no. 2 engine separated from the aircraft and the buffet stopped. The engine impacted in an open field, 6 miles from the airport. After separation, the 'B' hydraulic system lost pressure and the flaps would only extend to 10 deg. The aircraft was landed safely after an emergency gear extension and differential braking was used for steering. It appeared that the aft mount cone bolt for the no. 2 engine had failed from fatigue through the thread relief undercut radius. Fatigue cracks had initiated on diametrically opposite sides of the radius. Subsequently, the forward mount cone bolts and secondary support cable failed from overload.
PROBABLE CAUSE: "Previous damage to the aft cone (engine mounting) bolt, which resulted in mismatched surfaces between the bolt and isolation mount, loss of torque during cyclic loading of the mounting bolt, and subsequent fatigue failure of the bolt."
Forced landing on runway
» NTSB
| Status: | Accident investigation report completed and information captured |
| Date: | Saturday 5 December 1987 |
| Time: | 09:55 |
| Type: |  Boeing 737-2B7 |
| Operator: | USAir |
| Registration: | N319AU |
| MSN: | 22887/976 |
| First flight: | 1983-06-24 (4 years 6 months) |
| Total airframe hrs: | 12845 |
| Engines: | 2 Pratt & Whitney JT8D-15A |
| Crew: | Fatalities: 0 / Occupants: 5 |
| Passengers: | Fatalities: 0 / Occupants: 62 |
| Total: | Fatalities: 0 / Occupants: 67 |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | Deptford, NJ ( United States of America)
|
| Phase: | En route (ENR) |
| Nature: | Domestic Scheduled Passenger |
| Departure airport: | Philadelphia International Airport, PA (PHL/KPHL), United States of America |
| Boston-Logan International Airport, MA (BOS/KBOS), United States of America | |
| Flightnumber: | 224 |
USAir Flight 224 departed Philadelphia on a scheduled flight to Boston. While climbing through 4000 feet, the aircraft yawed and rolled to the right. Simultaneously, the crew noticed the no. 2 throttle slam and lock to the idle position. A continuous airframe buffet began. Soon thereafter, the no. 2 engine separated from the aircraft and the buffet stopped. The engine impacted in an open field, 6 miles from the airport. After separation, the 'B' hydraulic system lost pressure and the flaps would only extend to 10 deg. The aircraft was landed safely after an emergency gear extension and differential braking was used for steering. It appeared that the aft mount cone bolt for the no. 2 engine had failed from fatigue through the thread relief undercut radius. Fatigue cracks had initiated on diametrically opposite sides of the radius. Subsequently, the forward mount cone bolts and secondary support cable failed from overload.
Probable Cause:
PROBABLE CAUSE: "Previous damage to the aft cone (engine mounting) bolt, which resulted in mismatched surfaces between the bolt and isolation mount, loss of torque during cyclic loading of the mounting bolt, and subsequent fatigue failure of the bolt."
Accident investigation:
 |
|
Classification:
Engine separationForced landing on runway
Sources:
» Aviation Week & Space Technology 30 Jan. 1989 (p.71)» NTSB
Follow-up / safety actions
NTSB issued 2 Safety Recommendations
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Photos
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Philadelphia International Airport, PA to Boston-Logan International Airport, MA as the crow flies is 447 km (279 miles).
Distance from Philadelphia International Airport, PA to Boston-Logan International Airport, MA as the crow flies is 447 km (279 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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