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Another DC9 Question

Fri Jan 14, 2005 12:22 am

What is the life limit (hours/cycles) on the DC9 airframe? Can it be extended by service or is there a total end-of-life limit? Would a plane with 73,000 landings be considered nearing the end or does it have a long time to go? That seems like a lot to me - this plane was new in March, 1967.

I know NWA has no plans to fade out the DC9 but won't they have to get rid of the oldest ones due to age?

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RE: Another DC9 Question

Fri Jan 14, 2005 12:56 am

I can just pass on what an acquaintance with the FAA told me once so you can take it with a grain of salt.

A 737 (did not specify which model) was estimated to have about 50,000 cycles with normal maintenance.
A DC-9 (again did not specify any model) was estimated at 100,000 cycles with normal maintenance.

He commented that the Douglas used a heavier gauge/different alloy of material on the skin of the aircraft.

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RE: Another DC9 Question

Fri Jan 14, 2005 1:44 am

Don't believe there is a limit on hours or cycles. I believe that it is more, on-condition. There are other "aging fleet" issues that will probably drive them out of the skies before the sheet metal does. Wiring, tubing, and all of the things that deteriorate are likely to make them less and less desirable to the operators. I would not be surprised to see inspection schedules become more and more expensive, not only in terms of the actual procedure, but for frequency and the downtime on the airframe.

I used to read the FAA's MRR Summaries for the DC-9 and some issues, maybe 70% of the items detailed there were corrosion and cracks found in C and D checks. (at Republic and Eastern, mainly)

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I've also been told that when Sunworld ceased operations one of their DC-9-14 airframes was one of the top two or three for time/cycles and, for that reason, it was re-acquired by the factory to be tested to destruction. Can anyone confirm that? (Maybe N9102)

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RE: Another DC9 Question

Fri Jan 14, 2005 3:43 am

There is NOT any time/cycle limitation on the airframe. As long as it is properly maintained in accordance with its instructions for continued airworthiness, conforms to the type design it can keep flying until it is economically prohibitive. The original Design Service Objective (DSO) for the 707 I believe was 20,000 cycles. There are a couple of 707s that were flying for Boeing Aerospace Operations (Teaching E-3B Sentry AWACS Pilots) that had over 102,000 cycles.

Just an observation after working on Boeings, Lockheed, Douglas/McDonnell Douglas & Airbus; the Douglas airplanes are tanks, built tough and it shows to this very day.
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