high time 747's

[Willit Run]

OK,
Supposedly, Boeing wants to ground 747's that have more than 30,000 cycles. Anyone else heard this little rumor. This popped up before the China crash, so

this came from a guy who was at a meeting with some boeing boys!!

just fishing!!!!

[Wizard]

There is the ongoing Boeing CPCP programme which seems to deal with most concerns. Alongside that there is a fairly constant stream of service bulletins continuing to deal with keeping these older birds safe.

The latest we received a couple of days ago being SB 747-53A2431 R02 dated 13th June deals with problems found in high time aircraft relating to cracks and corrosion in upper deck floor beams at STA 340, 360 and 380 that might in some circumstances effect fuselage integrity. They also refer to Boeing Structural Item Integrity Advisory (SIIA) 747-175.

The aircraft refered to above was a 747-200 Freighter with 19,598 flight cycles and 79,975 flight hours. The problem was identified, rectified and the service bulletin issued accordingly.

[CR2]

Any idea whose 742F that SB refers to?

[basil fawlty]

How many 747s have achieved 30000 cycles? Seems quite a reasonable limit (or target!) but with an average sector length of 4? hours only the very high timers will be affected anyway. The obvious exception to this is the Japanese SR varients of course.
I thought that it was economics that always grounded aircraft and not engineering. Modern aircraft can fly on almost indefinately now if maintained and modified correctly, but there comes a point where the financial cost for this to happen exceeds revenue and they become unprofitable. Interesting rumour nonetheless, if older a/c are to be phased out at a definite point (and maybe this is the thin end of the wedge) then is Boeing just trying to create a market for its new aircraft??

[747FOCAL]

:D Boeing is not in the business of keeping older aircraft flying or enhancing the abilities of older aircraft. Boeing is in the NEW aircraft business. Due to the fact that the Boeing sales unit controls the strings around corporate, all of commercial aviation has suffered. Our customers have suffered as well in higher ticket pricess and environmental distruction of our world.

Boeing has countless fixes for issues found troublesome to the operators and have done little to nothing unless the help enhances Boeing's ability to sell new aircraft(ie. Boeing gives the fix to an operator to help them find money to sign up).

Boeing also has countless TSFC reduction packages that are not nor will they be ever offered to the commercial public. As early as 1985 Boeing knew how to reduce the 747-200 SFC burn in cruise by 8% but they didn't want to hurt 747-400 sales by breathing life into the -200s so they killed the program.

Look at the hushkit market that Boeing so nicely stayed out of so that they could sell lots of 757s and 767s..... Boeing thought that without their help the 727s and classic 737s would die.... Nope, Boeing threw 5 billion dollars out the door to the STC market and still haven't sold crap for 757s or 767s.

Boeing would love to put an absolute death date on each airplane but thats just not how it works. Only the FAA can do that.:D

[411A]

Have to say, 747FOCAL has hit the nail on the head...this time.
Boeing has never been all that receptive to prolonging the life of their airframes....except by FAA directive.

[Wizard]

CargoRat2 sorry have no info on which aircraft was referred to or whose fleet it is in. Will let you know if I can get anything further as I am also curious to know.

[Nimbone]

It's not the 30,000 cycles that has us concerned, it's the 115,000 hour limit they are proposing. Boeing says it's the wing. They also say it's going to cost a lot.

[Wizard]

This just received from Boeing Customer Support

"I am not aware of any limit that is in effect today. There is considerable maintenance that must be done at 20,000 cycles.

I am aware that Boeing have stated there will be a limit of 30,000 cycles sometime in the near future. If you want to operate above 30,000 cycles you will have to buy the document from Boeing that details the extra maintenance required. If you want to go above 35,000 cycles you must negotiate that with Boeing.

I heard the above in a Boeing meeting. It is not official and I suppose Boeing could change their mind."

.......end of quote

[411A]

Wonder if this is a similar wing problem that early model 707's had years ago?

[Nimbone]

It's not a wing "problem" - Boeing says it's the wing that imposes the 115,000 hour limit - not the pressure vessel.

Again, the 30,000 cycle limit makes some sort of engineering sense - imposing a life limit on the airframe, etc. but an hourly limit? We're having a hard time with that.

Plus the economics of going beyond 30,000 is one thing, the economics of going beyond 115,000 hours is something completely different!

[Nimbone]

411A - you're talking about the wing "glove" installed on the 707-100's? If so, that was a fix to some handling characteristics - not sure exactly what, but I vividly remember removing the glove panels and seeing the "old" wing skin underneath.

Was an interesting time, indeed. The 707 had a lot of interesting structure, including spot-welded skin-to-stringer joints, the good old scrim cloth in the lap seams, and other fun stuff I hope I never see (or have to repair) again.

[arcniz]

I understand the frustration at limited life cycles for expensive airframes, but let's try to be real about this: there will always be some limit - the only issue is - what number?

Your basic 747 is a few million pieces of something or other, carefully stiched together, all wearing out at different rates. Some pieces are near the surface and designed to be heavily maintained, others are not so easy to reach. Yet others, like the slowly crystalizing alloy of the bulkheads, pylons, fuse and wing beams, etc., can wear in ways that are very hard to assess; harder yet to predict. If you think the book service life numbers are perfectly true for all cases, then you oughta be walking for a living.

At some point in an aircraft life cycle it begins to take greater skill, money, luck and expertise to support an hour of seat miles production from a dear old aircraft than from a shiny new one. The 'loving care' quotient - and operating expense - goes up from then on until the boneyard takes it.

The spec goal that 100 percent of passengers should reach their destination alive for 100 percent of flights imposes some difficult maintenance constraints. Surely there is some tradeoff. Perhaps if that unreasonably stiff criterion were reduced to 99 x 99 percent, then some aircraft could go out to 500,000 cycles. But would net profits increase as a result? Probably not, because the hard-core fatalists represent only a small fraction of the flying public - at least among the people in the paying seats. The folks who mostly hanker to sip a mai tai while burning on a beach somewhere do not like to think of that as a calculably risky activity.

An airframe manufacturer's engineering people are in the uncomfortable position of knowing that certain things in the way of design now can be - and should be - done differently and 'better' than they were 35 years ago. It is hard for them - mostly young f**ts anyway - to justify extensions of service life for machines they perceive as obsolete and incurably fallible in some respects.

IMHO: Yes it is a conspiracy by Boeing to obsolete old aircraft - no it is not a totally bad idea.

Besides, the time-building pilots need something to fly in the Andes at night hauling produce and hot suv's for pennies per hour. Turn the old birds into freighters on the way to retirement, and put them out where they cannot do very much harm.