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-   -   BBMF Grounded (https://www.pprune.org/military-aviation/598432-bbmf-grounded.html)

Top Bunk Tester 16th Aug 2017 20:43

BBMF Grounded
 
Breaking BBC News

Lincolnshire breaking news: Latest updates - BBC News

chevvron 17th Aug 2017 05:21

Skew gear failures as happened during WW2?

Wensleydale 17th Aug 2017 06:49

Happy to see that the BBC are down to their usual sloppy standard of reporting with film of the Blenheim flying with Spitfires at Duxford - even their website report has a photograph of the Canadian Lancaster rather than the BBMF aircraft.

cats_five 17th Aug 2017 07:14

"Engine issue grounds Battle of Britain Memorial Flight planes"
...
"A Lancaster bomber, two Hurricanes and three Spitfire planes are all affected by the problem.

The BBMF has three other Spitfires with different engines which are currently unavailable for other reasons."
...
"The problem is "related to the Merlin engine" - which powers aircraft including the Spitfire, Lancaster and Hurricane - but "affects all current and serviceable display aircraft", the BBMF said."


Engine issue grounds Battle of Britain Memorial Flight planes - BBC News

Nothing on the BBMF website or Facebook page, at least not at the moment.

Fareastdriver 17th Aug 2017 07:55

They probably failed some dreamt-up emissions test.

VX275 17th Aug 2017 08:01

Have the BBMF had a MAA audit recently?

[email protected] 17th Aug 2017 08:05

Yes, someone probably didn't have the 'bow-tie' up to date or their 5 main RTL in the right order.:ugh:

Jetscream 32 17th Aug 2017 08:13

Sounds like Skew Gear problem that is critical to magnetos.... nobody likes the sound of silence when airborne other than glider pilots.....better safe than sorry and in all likliness a quick (:E) tear down, NDT / Dye test - tick - rebuild - display and back for tea and medals!

Hope they get back up in time for Scampers!

Icare9 17th Aug 2017 08:39

In wartime conditions, I doubt whether any Merlin had a long life, so to keep these engines (and aircraft) going for a further 70 years beyond that is wonderful.
Sad that these issues seem to be occurring one after the other, the Lanc being grounded for what seems years, now this.

Did the problem (which more technical minds than mine) identify as skew gears come to light due to the recent crash of a Spitfire? We also had the Mustang prang at Duxford - was that skew gear related?

Come back when all is fixed, BBMF, we miss you!

Davef68 17th Aug 2017 08:53


Originally Posted by cats_five (Post 9864420)
"Engine issue grounds Battle of Britain Memorial Flight planes"
...
"A Lancaster bomber, two Hurricanes and three Spitfire planes are all affected by the problem.

The BBMF has three other Spitfires with different engines which are currently unavailable for other reasons."
...
"The problem is "related to the Merlin engine" - which powers aircraft including the Spitfire, Lancaster and Hurricane - but "affects all current and serviceable display aircraft", the BBMF said."

One Griffon Spit and the Dakota are unservicable at the moment I believe.

IIRC they have 4 Merlin Spits (II, V, IX and XVI) and 2 Griffon ones

Drainpipe 17th Aug 2017 09:05


Originally Posted by Davef68 (Post 9864525)
Both Griffon Spits and the Dakota are unservicable at the moment I believe

An event I'm organising in September was expecting a Dakota flypast but the BBMF has said the Dak is u/s for the rest of the season. Shame.

PDR1 17th Aug 2017 09:40

Are these skew gears in the magneto drive or the camshaft drive?

PDR

Jetscream 32 17th Aug 2017 10:05

Come off the cam at right angles as a quill into the Mag - small shaft - Alex Henshaw wasn't a fan of such failures, as per this incident, so a quick grounding and Dye / NDT is well worth the effort in my mind, especially for the BBMF crews flying them and looking after them.
https://www.rafmuseum.org.uk/researc...e-trouble.aspx

H Peacock 17th Aug 2017 10:08

The Merlin camshafts are all driven by a combination of spur gears and bevel gears. A bevel gear on the main crank drives 2 vertical shafts, one lower one upper. The upper vertical shaft drives another bevel gear which in turn drives 2 angled shafts, one for each of the 2 cylinder head banks.

Both magnetos (one on either side of the engine) are driven from a lateral shaft which is driven from the upper vertical drift shaft by a pair of skew (helical) gears. I believe that both magnetos share their drive from just one set of the skew gears.

Nige321 17th Aug 2017 10:29

Does this help...?

http://www.avrosystems.co.uk/bomber/...earsmodded.jpg

Nige321 17th Aug 2017 10:47

For those with a strong constitution, Jeremy Vine is covering this on his Radio 2 show at 12:00...
If the trailer is anything to go by, it will be complete BS.
He was droning on about them being unairworthy, decrepit, old, not maintained, time for them to go etc.
Blood boiling now...

PhilipG 17th Aug 2017 10:54

If the reason that the BBMF Merlin engined fleet has been grounded relates to a specific Rolls Royce Merlin problem, does this have knock on consequences for other Merlin engined aircraft?

Further is the "problem" a Rolls Royce Merlin one or does it also apply to Packard manufactured Merlins?

Let us hope that whatever the problem is it is sorted soon.

H Peacock 17th Aug 2017 10:56

Ah, great image. A picture paints...

You can see the lateral magneto drive shaft driven at 1.5 x engine rpm are driven by a single pair of helical (skew) gears - therefore a single point of failure for both mags.

The only other helical gears are to drive the fuel pump from the lower vertical drive shaft.

GeeRam 17th Aug 2017 11:07


Originally Posted by PhilipG (Post 9864645)
If the reason that the BBMF Merlin engined fleet has been grounded relates to a specific Rolls Royce Merlin problem, does this have knock on consequences for other Merlin engined aircraft?

Further is the "problem" a Rolls Royce Merlin one or does it also apply to Packard manufactured Merlins?

Or is it even a problem related to the contractor that overhauls the Merlins for BBMF....rather than an intrinsic Merlin (or Packard) design issue...??

Hopefully a resolution will be found soon.

PDR1 17th Aug 2017 11:53


Originally Posted by GeeRam (Post 9864662)
Or is it even a problem related to the contractor that overhauls the Merlins for BBMF....rather than an intrinsic Merlin (or Packard) design issue...??

I suspect that's more likely to be the issue for it to have such a sudden and widespread effect over such a range of merlin marques.

PDR


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