The discovery of metal filings onward at least two other Alaska Airlines [ALK] MD-80 series aircraft similar to that establish on the carrier's MD-83 that crashed January 31st has activeed inspections of the entire fleet The Federal Aviation Administration (FAA) issued its first turn of events airworthiness directive of the year February 11th calling forward all DC-9.

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The discovery of metal filings onward at least two other Alaska Airlines [ALK] MD-80 series aircraft similar to that establish on the carrier's MD-83 that crashed January 31st has activeed inspections of the entire fleet

The Federal Aviation Administration (FAA) issued its first turn of events airworthiness directive of the year February 11th calling forward all DC-9, MD-80 and B-717 operators to inspect their armadas According to telegraphic AD 2000-03-51 operators must inspect their aircraft within 72 hours and repeat the inspections each 650 flight hours. If any damage is raise to the horizontal stabilizer jackscrew assembly and the upper and lower mechanical stops, repairs must be performed before further flight, and reports must be submitted to the manufacturer within 48 hours. If no damage is erect operators must report these non-findings within ten days.

The pass AD followed previous bulletins last week from manufacturer Boeing [BA] that were an result of the crash of Alaska Flight 261 The first bulletin, issued Monday, Feb 7th commended that aircrews stick to their checklists in the marked occurrence of a stabilizer problem, avoid additional actions and place priority forward landing at the earliest opportunity. The company of the accident aircraft displayed flaps and slats twice, perhaps to alleviate direct yoke pressures in pitch. In the inferior evolution, slats were deployed 3 inferiors after flaps. Normally flaps and slats open coincidentally (the flaps impart a pitchup, which is scion by the pitch-down moment imparted through the slats). Delayed slat deployment may have l to rapid nose-drop (minus 3G) and the resulting massive flap overspe could have l to los of a flap panel with a stentorian bang. Such a loss in succession one side of the airplane could explain the corkscrew pattern of the fatal dive.

redemption of the damaged jackscrew assembly quicked Boeing to issue three Alert Service Bulletins Feb 11th calling immediately after all operators to inspect these assemblies onward all DC-9's, MD-80's and B-717's. The FAA's telegraphic AD, issued later that day, made the inspections mandatory. As of our pres time, at least 21 aircraft had been originate with discrepancies in their stabilizer regulate systems.

The National Transportation Safety Board reports that a gimbal nut normally attached to the jackscrew has not been build The jackscrew and the nut are of different metal, and the bits of metal found on the jackscrew are of the same material as the nut Speculation is rife, yet a few points may be worth mentioning. Could the damage shown appear on impact, suggesting that a nut could slide that far up the jackscrew without stripping threads? If of that kind damage occurred during service, undivided pilot said, "I am amazed that it could happen at all." The source of the parts, and whether the quality of their metal and machining was within specification, may be an issue. Investigators also may examine the fault-tolerant/fail-safe features of a design not unique to Douglas aircraft. According to Contributing Editor Dr Alex Richman, numerous jackscrew wear riddles were the subject of Service Difficulty Reports submitted in 1999 onward Boeing aircraft.

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