NYC93IA184

When the wing flaps were retracted after takeoff, the captain noted airframe vibration. He dumped fuel and returned to land. Examination of the airplane revealed that the no 1 movable flap fairing was missing. The fairing was located the next day in a field approximately 3 miles from the takeoff runway. Examination of the fairing revealed that the two, lower hinge bolts were missing. The hinges and bushings showed no evidence of deformation or failure.

On Saturday, September 11, 1993, at 1930 eastern daylight time, a Boeing 747-200, N17025, operated by Continental Airlines, Inc., sustained minor damage when an outboard wing flap track fairing departed the airplane. None of the crew of 17 or 370 passengers were injured. Visual meteorological conditions prevailed, and an IFR flight plan was filed. The flight was being conducted under 14 CFR 121.

The airplane departed Newark International Airport, Newark, New Jersey, destined for London, England. After takeoff, the pilot reported problems with the wing flap system and airframe vibrations. He requested clearance to dump fuel and return to Newark for landing. The airplane landed without incident.

Investigation of the airplane revealed that the number 1, outboard wing flap track fairing was missing. The wing flap track fairing was located the following day in a field in Staten Island, New York. There were no injuries on the ground, nor was there damage to any property.

Investigation revealed that two lower hinge bolts were missing from the forward section of the fairing that secures it to the track. A bonding jumper was also missing.

A Safety Board Investigator and Federal Aviation Administration Airwothiness Inspectors observed no evidence of mechanical failure of the hinge, nor was there observable deformation of the hinge assembly.

N17025 was delivered by the manufacturer for airline service on August 1, 1973. At the time of the incident, the airplane had accumulated 68,434 hours and 17,992 cycles. Continental Airlines, Inc. had been operating the airplane since December, 1989. The last major maintenance inspection performed on N17025 was a "C" check completed on February 5, 1993. Since that inspection, the airplane had accumulated 2848 hours in service and 408 cycles. A review of Continental Airlines, Inc. maintenance work cards revealed no record of the removal of this fairing, since the inspection in February.

A review of Federal Aviation Administration Service Difficulty Reports, from January 1, 1986 until September 23, 1993, revealed one other wing flap track fairing partial failure, as a result of a crack in the composite fairing.

Mr. Rick Howes, a Boeing Aircraft, Inc. Air Safety Investigator, reported that in the 10 year period from 1983 there was one fairing that had failed in flight, but not as a result of missing hinge bolts.

The Boeing B-747 Maintenance Manual was examined. No discrepancies were found in the installation procedures for the fairing hinge bolts, which are secured by tiebolt locks.

Continental Airlines, Inc. engineering department conducted an examination of the fairing. In a report Mr. Bilal Yousuf stated:

I concluded that the subject fairing separated from the aircraft because the two, lower forward hinge bolts...became loose and migrated out of position under vibration.