My all time favourite 762, VH-EAJ "City of Wollongong", is to be retired later this month, following the retirement recently of EAK. EAJ was a regular on the BNE-SYD run.

I won't forget looking out the window from my favourite seat 23A, and feeling the rush as those big PW fans spool up....

EAJ has been in service since 1985, so it's had a good innings.

Aahhhh, it's like the old CAAC Tu154's - must be safe otherwise it would have been in pieces ages ago.

Strange to think that at the "magic" age or number of cycles, a perfectly good aircraft (all be it looking like crap inside) suddenly has only scrap value.

According to a post in aus.aviation from someone who usually knows such things, EAJ has flown 58877 hours and compleed 26082 cycles.

58877 hours is equivalent to 6.7 years in the air - not bad for an aircraft which is 18 years old.

Dave

I think it has more to do with operating economics than anything else - with the A330's coming on line to provide greater capacity on the monorail, at a much lower cost/seat-mile (I forget what the TLA is, might be ASM) a point is reached where it is more economical to operate newer aircraft compared to the cost of an extensive interior refit and higher running costs.

Dave

Intuitively yes, except that due to the wonders of engineering fatigue, what may look like a perfectly good aircraft after 26,000-odd cycles might actually have you shuddering if you could see the small cracks developing in critical areas.

Nostalgia notwithstanding, I'm more than happy to see aircraft of this era retired after 25,000 cycles. It's the maintenance checks required to certify/render them metallurgically safe that just don't make economical sense.

When I said "a perfectly good aircraft..." I did mean that if it wasn't "perfectly good" then the guys up front wouldn't fly it -- right? Also, that the Government safety regulator wouldn't let it fly?

Great answer MrsDrD>, using your acquired skills I see...

All of QF's 762's are for sale here. I don't think we will see them being sold with the ammount of newer models sitting in storage. This site shows they have been listed for sale for 26 months and given QF's maintanance record you would think that if they were going to be bought they would have by now.

Cheers

[This message has been edited by vander555 (edited 07-10-2003).]

I'm not meaning to be critical of anyone who perceives that a plane can seem to be "perfectly good" - sorry if I gave that impression.

You are correct - regulators will ground aircraft that are known to be over schedule for major maintenance inspections, once they find out about it. Remember the unfortunate Ansett story? Whether flight crew will refuse to operate an aircraft or not, I don't know - I do not know how much knowledge they have of the individual service histories and cycles flown of the equipment they operate on any given day.

The fact remains that all these aircraft were designed with specific fatigue cycle limits set down, and 20,000+ cycles begins to approach those original set limits. Major inspections being to be scheduled with increasing frequency, which are costly and time consuming, and the economics of an airline like QF keeping them in the air start to wear a little thin, and hence they retire them.

To be a little more indepth: the essence of metallurgical fatigue is that it starts as a microscopic problem, and grows from there. Depending on where the defect is located in the structure, by the time it becomes readily visible, it could be a serious problem. Materials engineers know this, they know the average lifespan that a certain material will have under a certain cyclical load, and this is where the "rules" come from regarding design lifespan.

Aircraft manufacturers like Boeing continue to do research work on the fatigue performance of these older aircraft. I know they had/have at least one 7-series aircraft that they purchased from an operator who was retiring it at about 20,000 cycles, and they have continued cycling it on a rig to better understand and predict where the problems will occur, in order to give additional directives on maintenance for older aircraft.

Of course, newer generation aircraft use better materials variants with a higher fatigue lifespan. I recall a paper from a few years ago where Boeing's design service objective for the next generation 737 was 75,000 cycles, and they were halfway through conducting safety tests to 3 times that limit.

Fatigue is of course not the only issue for aircraft design, but it's one fo the big ones. And it's one that you don't want to get wrong in an aircraft of all things - it's what makes it the classic study example for young engineers.

Hope that is of interest.

[This message has been edited by MrsDrD (edited 07-10-2003).]

MrsDrD, I have always had a fascination with aircraft crashes - why, how etc. Still love travelling in them though (the planes, not the crashes...). Even more interesting is reading the investigations as they unfold (eg on PPrune).. Case in point being the Air China 742 break-up (?) and whether it was the cargo door or a skin doubler that gave way - and possibly fatigue related - as you touched on in your posting. Also made me think of travelling several years ago on an AR 732 with a long skin doubler along the windows - I presume it was to reinforce the metal bonding that wasn't quite up to scratch (that Hawaiian learnt about).

I really appreciate the postings from FTers who have a passion about their job ( and / or hobby?) and share it with others in this board.

og, that's a little more than a passion for MrsDrD, she is indeed highly qualified to give you chapter and verse (I know more than I am letting on, having had the pleasure of contact with MrsDrD).

You could do worse than to hang off her every word on this subject...

OK, so when's the next FT meeting?

With MrsDrD involved...it would be BNE or HKG. Considering you're in SYD, I'd think BNE is closer...

If you're going off topic (what, not here!), I'll be travelling again probably in both of the next two weeks, but will be short notice as haven't finalised yet [have to visit PER & ADL (maybe); MEL, SYD, CBR (definites)].

I will post a separate thread when I know where I'll be, to entice another QC meeting or similar near-City establishment with locals...or timely visitors...