View Full Version : Marking Parts 'Fit to Fly'

16th Jan 2015, 07:17
Nostalgia for those bits we used to play with in our avionics research labs, autopilots and so on. Design Engineers and lowly apprentice saggermakers' bottomknockers were allowed to make non-flying prototype equipment, but anything which was going to fly, even experimentally in our own aircraft, had to be assembled by properly certified technicians and wiremen.

Each flying part had to be labelled as such, and even the lowliest teeny nut, bolt and washer had a little imprint of linked circles, rather like the Audi trademark. Was this a company thing, or a national one, or was it even an intenational standard? And how is it done today?

16th Jan 2015, 08:59
I have a collections of alsorts of parts from Merlins ex Spits /Lancs to Griff 57/58 to undercart part from Tornado's they all have part numbers and drawing number engraved into them plus circles with stamped numbers and initials plus date so possibly not much has changed, even undercarriage nuts and bolts + washers with the same type of numerics and circles.

Peter RB

17th Jan 2015, 08:19
The parts were checked by inspectors - some from the company, some from the Aeronautical Inspection Directorate/Department - and each inspector had his/her own stamp. There's a couple of examples at Air Inspection Department (AID) (http://forum.keypublishing.com/showthread.php?77755-Air-Inspection-Department-%28AID%29)

17th Jan 2015, 08:48
Getting qualified as an AID inspector while serving in the RAF was much sought after, as it was a passport into the civilian job.

I only came across such people at Akrotiri circa 62-63. They were all at the MU there. I believe it was 13 MU, but time blurs the memory.

In a later life, I installed an IBM process control computer that controlled Creep Furnaces, the results of the creep tests qualified the tested alloys to be used by Rolls Royce in their RB 211's. So the AID guys came to my customer to inspect the system, and when satisfied with the process, I had to open the system covers so that they could dully rubber stamp the computer!

It was the only AID approved computer that I ever knew of.

longer ron
17th Jan 2015, 11:33
Henry - did you mean 'Unified' markings on the nuts and bolts ?


these AGS parts would have been UNF etc

rgds LR

18th Jan 2015, 19:28
Ah, thanks Ron, that's it! :ok:

18th Jan 2015, 20:27
Ian16, it was 103 MU, formed just after WWI and designated as X Depo, based in Egypt during WWII and closed in March 1975, I was one of the very few left on the strength when it disbanded.
The CO was Wing Commander Ron Bowers who served on the MU as a Cpl engine fitter recovering aircraft from the desert during the war.

19th Jan 2015, 13:03
it was 103 MU,I wasn't too far of with 13 then was I?

Remember it was half a century ago:confused:

I only ever passed the place on the way to & from the Electronics Centre.