BAE 146’s

four oil leaks connected by an electrcal fault

well firstly the term “fatigue” relates to accumulated cyclic damage sustained during the course of normal operation which will evetually cause an item to fail, Aluminium structures are prone to fatigue whereas steel structures are less so, and below certain thresholds do not accumulate fatigue damage at all.

Aircraft fatigue can be calculated in a number of ways, the two most commonly used are Fatigue Index (FI) in the case of aircraft equipped with apparatus to measure the forces going through its structure, and Flight Hours, in the case of aircraft not subjected to high stress manouevering loads such as airliners although some military types are covered by FH.

FI for an airframe is calculated during destructive static testing of one or more airframes to gain a Fatigue Value for the airframe type, the critical componenet of the airframe which exhibits the lowest fatigue tolerance will generally be used as the yardstick for that type’s total FI, which is set at 100FI, the fatigue measuring apparatus is then calibrated for the airframe and installed, it will monitor G-loadings, shock loads, ect and display a cumulative total of FI units consumed, the aircraft will then be determined as life expired or “lifex” when this value reaches 100 unless the aircraft has been modified to allow a higher total of FI.

Aircraft lifed by flight hours will generally have airframe stress measuring apparatus but will be flown to a pre-determined houred lifespan, the testing process to acquire this hour number is much the same as for aircraft being FI lifed, with the hourage at first failure of a critical airframe componenet being accepted as the maximum houred lifespan, as an example the A320 Airbus series is lifed to 85,000 flight hours, once an A320 aircraft reaches that total it is considered lifex and can no longer be safely flown, it seems generally that US military aircraft manufacturers tend to use houred lives instead of FI lives, the F-15E Eagle having an houred life of 15,000 flight hours and a B-52 37,500

Im amazed that nobody has realised that the aircraft depicted is, of course, the upgraded Griffon engined Buffalo that was used to great effect in the Boer War….

I think thats refering to the posts about the engines being duff and needing hugely expensive deep overhauling etc etc etc.

however the engines are not duff and do not require repair, Rolls Royce have looked at them and her happy for them to continue in use. No decision has been made about the engine removed because of deposits found in the oil.

thanks bubbles, i gather then that the corrosion was/is very minor?

Isn’t a cost effective repair possible?

Rolls-Royce wont sanction an overhaul, the engine with corrosion may be repairable but but its a big if

The first prototype YF-111A (63-9766) survives at the Edwards Air Force Base Museum. The Chanute Air Museum in Rantoul, Illinois has the second YF-111A (63-9767). It was also the first to be flown by an Australian too. I had no idea the third prototype survived, or that it was in Australia either… excellent! Two of the prototype F-111B’s survive also, although only one is complete. The first FB-111A (67-0159) survives too. And finally, the prototype EF-111 survives at Mountain Home AFB. So… quite a few more prototype F-111’s than I had realized.

Cheers,
Richard

have asked a contact at Ambereley and he has confirmed that the aircraft’s tail number is 63-9768

Yeh, both 904 and 728 had the ‘mods’ pushing them out to 125 FI 😉

wasnt a large part of the reason 904 was picked by BaE was that she had/has one o9f the most leak free fuel systems of the last operational Lightnings back in 88?

No, John has it right, it was the 100 unit FI that was critical not hours flown.

In fact there were only a handful of the last in service F.6’s that had been fatigue extended to 125 units with the fitting of the wing reinf plates, that ever exceeded the 4000 hr mark.

XR757 I think was the highest houred at 4316 when it made it’s last flight in Dec 87.

Interesting little tidbit, thanks firebird.

how many of the ground running Lightnings around have any FI remaining?

id assume that Thunder City’s other F.6 and T.5’s would have some meaningful amount on them, XP693 should be practically brand new!