Saturday, April 05, 2008

FAA History Lesson -- April 5

From the FAA Historical Chronology, 1926-1996...

”Apr 5, 1991: An Embraer 120 commuter plane crashed on approach to Brunswick/Glynco Jetport, Ga. All 23 persons aboard the Atlantic Southeast Airlines flight died in the accident, including former Sen. John G. Tower (R-Tex.). Citing several incidents, FAA during May required inspections of certain Hamilton Standard propellers used on the Embraer 120 and other aircraft In Apr 1992, the National Transportation Safety Board cited the probable cause of the crash as malfunction of the left propeller control unit. As contributary factors, the Board listed deificencies in the design of the control unit and FAA's approval of that design. “

If you get a chance to see any of the hearing Chairman James Oberstar is holding (I’m sure they’ll be on YouTube if they aren’t already), this is a good accident to keep in mind. Take note of this quote from above: “Citing several incidents, FAA during May required inspections...” Incidents aren’t accidents. Incidents are warning signs that there may be accidents if we don’t address the problems.

The accident from this history entry was followed by another in 1995. Ironically, it was also in Georgia.

Probable cause

The probable cause of the accident was determined to be the failure of the propeller due to undiscovered metal fatigue resulting from corrosion. There had been at least two previous failures of the same propellers, but those aircraft had been able to land safely. The propellers had been recalled and serviced at a Hamilton Standard facility, but the inspection had been incomplete and the refurbishing work ineffective.

The NTSB criticized Hamilton Standard, who had maintained the props, for "inadequate and ineffective corporate inspection and repair techniques, training, documentation and communication", and both Hamilton and the FAA for "failure to require recurrent on-wing ultrasonic inspections for the affected propellers". The overcast skies and low cloud ceiling at the crash site also contributed to the severity of the crash. “

Don Brown
April 5, 2008

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