Rough cam lock surfaces on gas caps

[plasgears]

I made a field visit to a homebuilt nearing completion. [EAA Tech Counselor inspection]. Everything was fine except that the gas cap cam lock interfaces were very rough with saw tooth appearance. It was 'as drawn.' It had 'Made in China' written all over it, which translated means no attention to specs and no concept of QC. The airplane model is US made in the mountain west.

Manufacturers have to resist the dirt cheap appeal of sourcing in China and think of the consequences. Cessna would be smart to set up duplicate lines in Wichita and China, if they are addressing a China market. I hope they openly report their mfg experiences with China.

 

[MikeHalloran]

I'm a little more confused than usual.
If the appearance is 'as drawn', then the part meets the spec, right?



Mike Halloran
Pembroke Pines, FL, USA

 

[plasgears]

The term is meant to be as post drawn in a cupping die. The gas tank ring on top has a flange for attachment to the tank/structure. The cam surface I believe is secondary processed for smoothness.

 

[AviatorJim]

If it was a homebuilt aircraft, why would it have anything to do with Cessna's experience in China? Did you ask where the guy bought that part? There is a big group of guys building homebuilt aircraft getting thier parts from hardware stores, lumberyards, motorcycle shops and marinas. I know a guy who made the backbone of his aircraft out of an aluminum extension ladder. And there is no way you can ignore the homebuilt airplane made from a fishing boat at Lakeland.
..
That said, if it is a kit built aircraft, and the kit manufacturer provided the part I am surprised. All of the kit provided parts (not raw materials) I have seen have been of a very good quality, even if not made to the same specifications as a production aircraft.

--Jim (EAA guy too)

 

[plasgears]

Jim,
I am sensitized to 'made in China' from personal experience on an automotive second tier assy. Chinese acetal material was introduced by our plastic parts supplier without due regard to QC, and there was widespread infant mortality. The company lost the contract, all plants went into dormancy, and thousands lost their jobs.

I believe the gas cap assy was supplied with the American homebuilt kit. The cam surface was jagged like a saw tooth. The acceptable detail is either secondary machined or cleaned up in a trim die during progressive stamping. This one had 'made in China' written all over it.

 

[KirbyWan]

Widespread infant mortality? From a change in plastic on an automotive part? I must be confused because this does not sound plausable to me. I remember there were a lot of child deaths because of adding melamine to infant formula to increase the (apparant) protine content.

Does it literally have 'made in China' written on it or do you mean it appears to made in china because of the poor quality of the part?

Poor quality parts can be a problem, and it's important to find out where they came from so you and others can avoid them, but remember that the part was not made by china, but by a company (possibly) in china. There are many high quality Chinese companies that make good parts and a few crappy companies here in the U.S. that make junk. Let's not use China as a derogative for poor craftsmanship.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[plasgears]

'Infant mortality' is an engineering expression that describes numerous structural failures early in production service.

China needs to learn the rudiments of QC and conformance to specifications. I have seen numerous examples of Chinese non-conformance as a result of convenient alternates introduced into the system. It gives new meaning to the words 'Chinese Junk.'

 

[KirbyWan]

Wow, I had never heard the term used in that context. Thanks for the instruction. Now it at least makes sense to me. I was racking my brain to come up with a connection between plastic car parts and dead babies. Confusion corrected.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.