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Aviation History
1988
1988 - 1764.PDF
Aloha: Boeing "concerned" before accident by Julian Moxon in Washington D.C. Boeing expressed serious con cern over the condition of Aloha's ageing Boeing 737 fleet several months before the acci dent last April, when a 737 lost a section of its upper fuselage. In a highly unusual action, the National Transportation Safety Board (NTSB) has included in its pre-hearing report Boeing documents in which the manu facturer makes clear to Aloha its worries about corrosion in its high-time aircraft. Boeing visited the airline several times last autumn when the airline was carrying out heavy maintenance checks on two of its three oldest 737s. Boeing engineers attended the check as part of the company's ageing fleet evalu ation programme, which gathers information on high-time Boeing aircraft, some of which are still in service well past their original design life. Of ten 737s operated by Aloha, seven are more than 15 years old, and three (two since the accident) were the highest flight-cycle aircraft of all Boeing jets flying throughout the world. Ironically, the accident aircraft was the only one of the three not seen by Boeing. By last December this aircraft, N73711, had accumulated 87,772 flight cycles, while the other two, N73712 and N73713, had built up 88,455 and 83,700 respectively. Boeing originally put a 75,000-cycle economic design life on the 737. In its "general observations" during Aloha's inspection of N73712, Boeing noted "extensive pillowing of lap splices and some circumferential splices in the fuselage that are evidence that extensive corro sion has occurred," and that "belly skin corrosion was readily apparent by the quantity of skin panels applied externally". Also in this aircraft, "numerous cracks and missing fasteners heads were found on the fuse lage, notably around cutouts for doors and access panels". The other aircraft, N73713, was less damaged, although it had corrosion on the wing spars. Boeing remarked that "systems are in excellent condition and well maintained," but added that no formal corrosion-prevention programme was in effect for the aircraft. In a letter to Aloha president Maurice Myers last November, Boeing was concerned about corrosion in Aloha 737s even before the "open top" accident Boeing noted that "Aloha has a high-frequency schedule and operates in a highly corrosive environment. These factors certainly contribute to the corro sion and fatigue damage observed on the two aircraft surveyed." The letter expressed Boeing's "reassurance" that some of the recommendations arising out of its observations were being carried out. These included suggestions that Aloha should: • extend the layup periods for heavy maintenance (one of Boeing's concerns was that current Aloha maintenance philosophy tended towards resolving "short-term" crises, rather than correcting "long- term" problems); # return the highest-cycle aircraft to the maintenance shop in the spring (of this year) "to accomplish permanent repairs and complete deferred work". Boeing's relief turned to concern, however, when in March Aloha said that it had decided to defer heavy mainte nance checks on its older aircraft until the last quarter of 1988. The manufacturer returned to Aloha in early April (two weeks before the accident) to stress the need for prompt action. Aloha claims that Boeing assured the airline that its high- cycle 737s were "safe to continue in operation", and did not recom mend that any aircraft be taken FA. i. y action on old aircraft The US Federal Aviation Administration has acted quickly to quash rumours that it was planning to issue new regulations grounding older airliners after a specific number of flight-hours or cycles. Administrator Allan McAr- lor denied published reports that the FAA was planning anything more than paying greater attention *o raet«3- fatigue problems present in all older aircraft, and working out better maintenance proced ures for ageing aircraft. The FAA has not yet decided whether to require .•uMiticnst teyir-g ui Axiet atrcids, ant' •& nrt iisct-iy io AO so until next year at the earliest, said McArtor. Avmark says that the a»?iag,^ i£>> sf r\s '•> J'-c-.i of 2,851 passenger transports is »2 5 V'izfs. T.'nv.e th*' cf the 726-strong US cargo fleet n 16- h *'eai$—15 ?er -eat higher. There is therefore concern over any move to out of service. Boeing rejects this. "Without having performed a full inspection on an aircraft, Boeing would never assure an airline that an aircraft was safe to operate," it says. Further disagreement between Boeing and Aloha centres on a maintenance evalu ation carried out by Boeing last November, at Aloha's request. This resulted in 37 recommen dations, including one that the airline should urgently employ a structural engineer to ensure that proper attention be given to the structural integrity of older aircraft in its fleet. Aloha says that many of the recommendations were "inap propriate", while others were "wrong", or misrepresented Aloha Airlines' policies and procedures. "Others were simply untimely—Aloha having already accomplished the required work or changes." Nevertheless, the airline con cludes that "many valuable programme and procedural suggestions" came out of the study. The NTSB hearing is sched uled for later this month, in Seattle. Interestingly, the Boeing documents were made public under provisions contained in the US Freedom of Information Act. "We have reviewed the records, and have determined that they are an integral part of the Board's investigation of the April 28 accident," says the NTSB. 2 FLIGHT INTERNATIONAL, 9 July 1988
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