Primarily for general aviation discussion, but other aviation topics are also welcome.
#1843640
Trent772 wrote:Metres from new homes........

No school and hospital :wink:


But how far was it from thePuppy Farm???? :lol: :lol: :lol: :lol:

In any case, what's with that foreign muck, why not use good old feet and yards...... :D
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By Josh
#1843674
There's a very interesting post on PPRuNe about problems with the Centaurus specifically due to the supplies of the required oil specified by Bristol back in the day no longer being available. Apparently the sleeve valve engines are very sensitive to the grade of oil used and despite using the closest spec to the requirement and running well below combat power settings and lowering the TBO it clearlyo ain't working.

Doesn't come as a huge surprise to me given they took 10 years just to make sleeve valves work at all.

(At this point if you're interested in WW2 piston engines I highly recommend The Secret Horsepower Race which a brilliant history of British, American and German engine development)
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#1843892
plus7g wrote:3 days after its post-restoration flight from the Culdrose " crash" :( :( :( :(


I actually saw the thread title and thought it might be an update to that crash - as in the aeroplane was flying again... not that it had been crashed - again... :shock: :(
By pullup
#1843912
Josh wrote:There's a very interesting post on PPRuNe about problems with the Centaurus specifically due to the supplies of the required oil specified by Bristol back in the day no longer being available. Apparently the sleeve valve engines are very sensitive to the grade of oil used and despite using the closest spec to the requirement and running well below combat power settings and lowering the TBO it clearlyo ain't working.

Doesn't come as a huge surprise to me given they took 10 years just to make sleeve valves work at all.

(At this point if you're interested in WW2 piston engines I highly recommend The Secret Horsepower Race which a brilliant history of British, American and German engine development)


Interesting , but as this accident was only a few days out of maintenance I doubt it was the cause...
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By Josh
#1843940
I am not an expert in engines, but I would be very wary of ruling anything in or out just because the aircraft is post maintenance. The long term consequences of running an engine that was fundamentally not designed for the type of life it has now slightly out of spec are not something I would hazard to predict.
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By Morten
#1843948
pullup wrote:but as this accident was only a few days out of maintenance I doubt it was the cause...

There's a fair amount of info out there which shows that the highest probability of any sort of issue is exactly just after maintenance. Eg https://www.avweb.com/ownership/the-sav ... intenance/ - and various others. Intricacies and oddball factors in the way the engine is operated would exacerbate this effect, too.
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By kanga
#1843955
Crash one wrote:Scary thing is, they were still in service when I joined up!


.. and I can remember flying between two Centauruses in the '60s, in an Airspeed Ambassador of Dan-Air; of which one also flew into Stansted while I was there in 1970. They obviously still met the ARB's 'Public Transport' criteria then.
#1843983
kanga wrote:
Crash one wrote:Scary thing is, they were still in service when I joined up!


.. and I can remember flying between two Centauruses in the '60s, in an Airspeed Ambassador of Dan-Air; of which one also flew into Stansted while I was there in 1970. They obviously still met the ARB's 'Public Transport' criteria then.

And, c. 1966-68, I can recall seeing a Dan-Air Ambassador return to LGW soon after take off and do a single engine landing.
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#1844022
Morten wrote:
pullup wrote:but as this accident was only a few days out of maintenance I doubt it was the cause...

There's a fair amount of info out there which shows that the highest probability of any sort of issue is exactly just after maintenance. Eg https://www.avweb.com/ownership/the-sav ... intenance/ - and various others. Intricacies and oddball factors in the way the engine is operated would exacerbate this effect, too.


https://blog.aopa.org/aopa/2014/01/14/the-waddington-effect/

When he plotted the number of unscheduled aircraft repairs as a function of flight time, Waddington discovered something both unexpected and significant: The number of unscheduled repairs spiked sharply right after each aircraft underwent its regular 50-hour scheduled maintenance, and then declined steadily over time until the next scheduled 50-hour maintenance, at which time they spiked up once again.

When Waddington examined the plot of this repair data, he concluded that the scheduled maintenance (in Waddington’s own words) “tends to INCREASE breakdowns, and this can only be because it is doing positive harm by disturbing a relatively satisfactory state of affairs. There is no sign that the rate of breakdowns is starting to increase again after 40-50 flying hours when the aircraft is coming due for its next scheduled maintenance.” In other words, the observed pattern of unscheduled repairs demonstrated that the scheduled preventive maintenance was actually doing more harm than good, and that the 50-hour preventive maintenance interval was inappropriately short.

The solution proposed by Waddington’s team—and ultimately accepted by the RAF commanders over the howls of the maintenance personnel—was to increase the time interval between scheduled maintenance cycles, and to eliminate all preventive maintenance tasks that couldn’t be demonstrably proven to be beneficial. Once these recommendations were implemented, the number of effective flying hours of the RAF Coastal Command bomber fleet increased by 60 percent!
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