View Full Version : BBMF Lanc maintenance...

13th Feb 2007, 12:13
Hello all
I'm curious, after having seen a pic in PILOT, showing the BBMF Lanc getting an overhaul through the Winter.Why does it apparently get a Major every year,given that it flies a comparatively small amount of hours per annum, with no heavy load and restricted amounts of passengers and restricted manouvers? Is it overmaintained?

Taff Missed
13th Feb 2007, 12:17
No more than any other military aircraft. Over-maintenance is the name of the game but don't get me going on that.:ugh:


13th Feb 2007, 13:29
I belive te decision to use Atlantique to overhaul PA474 was because they could complete the major items required this time round that had accumulated over the years since it was last stripped down, anyway it's been followed on another forum with some interesting pictures.


14th Feb 2007, 00:20
Lancasters weren't designed to last very long between overhauls. I understand that during the war they went to MUs to be stripped and rebuilt at 400 hour intervals. From a write-up on the unit at Bracebridge Heath near RAF Waddington, I read that the process meant that the wings, tail and fuselage sections were unlikely to ever be reunited in the same airframe and the rebuilt aircraft received the identity of the cockpit section. I know that when I worked on PA474 back in '67 to '69 the data plates on various major parts didn't match. In particular, PA474's rudders weren't even Lancaster items, but were ex-Lincoln units fitted to provide increased rudder authority during the time the aircraft flew with the 'Midge Wing' fitted. I notice they are still in place today.

14th Feb 2007, 09:46
Blacksheep, I'm glad someone else has noticed. I presume that the larger rudders give a better level of control for the display work she now performs else surely someone would have found, rebuilt, remade or stolen some proper Lancaster rudders to make her look more authentic. Can the BBMF people confirm or deny?

18th Feb 2007, 21:25
Hi all
Thanks for the replies. Does the Lanc and it's sister aircraft in the BBMF use a military IRAN-style overhaul schedule or is it unique to the BBMF? Are the aircraft operated with finite fatigue limits?

19th Feb 2007, 20:40
It doesn't get a Major every year. It gets a Major every 8 years. It has an annual at the end of each summer season. The Major used to be every 6 years but it has just undergone a schedule review which has pushed the interval out.
The FI is checked by BAeS and decisions are taken how best to keep the aircraft in a flying state. This year we had to change control rods and a rudder brackets and aileron hinges based on advice from BAeS based on FI used. The main spar has about 70 years based on current consumption.

19th Feb 2007, 23:45
Thanks for that rum_monster, the BBMF maintenance team do a magnificent job!. :ok:

Being one of the team that prevented PA474 becoming a rotting gate guard, I still have a soft spot for the old girl. Long may the BBMF keep her flying - hopefully at least until she needs another main spar replacement! When we did the original work it was only 20 odd years since the end of WW2 and it amazes me that 38 years have now passed since I last crimped a terminal or waved an AVO on PA474. I did much of the rewiring, but I suppose most of my rewiring handiwork will have now been replaced in its turn. Still, its nice to know that she'll still be flying long after I'm gone.

20th Feb 2007, 17:34
You must have done a good job as she was only rewired in the 90s. We have just had a wiring survey done as part of the ageing aircraft audit with no major issues.
I have added a few more photos to another forum http://forum.keypublishing.co.uk/showthread.php?t=67897
We found a list of people who had previously worked on 474 stuck in the dingy bay in the wing.
Nice to hear from you and I am sure she will still be going strong long after us.

21st Feb 2007, 03:26
Thanks for the pic links rum_monster; I'm not on those name lists though. I worked on her from 1966 to 1969 in between Vulcans - a lot of the work was voluntary and done in our own time.

I first rewired the generator and battery circuits. THe original wiring had rubber insulation that had hardened and in many places, split. Chunks of rubber would fall off if you touched it. The main power panel on the stbd side of the cockpit was interesting. The original ammeters didn't use shunts and the generator cables went directly to one side of the ammeters and the other to the bus bars. When we first opened the panel, it flexed the main cables and a whole lot of perished rubber insulation fell off! I fitted ammeter shunts and rewired the whole panel. I also installed new carbon pile voltage regulators to replace the original flip-flop switch type.

For navigation the Staish wanted to fit TACAN but there was no 115v 400Hz power supply. We designed an inverter installation and fitted it under the WOP's station. The system included a circuit that automatically dropped the inverter if the pilot pressed a feathering button because the generators hadn't enough power to handle both the inverter and a feathering pump. We replaced the heavy wiring with Nyvin and the lighter cables with Pren. The original Plessey plugs and sockets used solder connections and we changed those out with what were then the latest Plessey plugs with crimped terminations.

I never enjoyed working on any aircraft as much - either before or since. We all had to really use our tradesmanship.
Nay, craftsmanship is more like it.