Date: Fri, 16 Jul 2004 08:36:04 -0500
Reply-To: John Rodgers <jh_rodgers@BELLSOUTH.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <jh_rodgers@BELLSOUTH.NET>
Subject: Re: German/French collaberation and Crashing Helicopters
In-Reply-To: <BAY7-F27ALZ9fhzgAfi00018406@hotmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Russell Patten wrote:
> The other day I was considering the purchase of a used fuel pump
> from an
> e-bay seller, ID: 'karmanvan'. I had e-mailed him to ask the bosch part
> number on the pump to determine if it was the correct part for my
> vehical.
> He informed me that Bosch had different exact-match pumps with different
> last 4 digits of part number indicating where they were made, all exact
> matches for the pump that belongs in my van.
> Smells like a skunk to me. The Bosch part numbers I have for all of
> the
> electrics in the van (Thanks Joel) refrence only a single number for the
> fuel pump. Ends in 016, if memory serves. Gentleman informed me the
> same
> pump built in france ends in 011. Another for Italy.
>
> Why would Bosch have the same pump made in different places and give it
> different part numbers?
>
>
>> We got to where we could predict a transmission failure with an 85-90%
>> accuracy. Pretty good for back in those days. Made the Army and Page
>> very
>> happy - and a especially a lot of pilots!!
>
>
> That sounds like a pretty interesting job. I like the pilot that
> hovers
> all day as part of his advanced training. Punishment for something, I
> guess.
Russell, actually the hovering all day was a deliberate part of a test
program. Page was paying guys to run the machines in the sands pits all
the way up to the point of destruction. No punishment involved. Just
testing, and somebody got paid well to spend the hours in the seat to do it.
> I'm also curious about predicting a transmission failure in a helicopter.
> How do you let it happen without catastrophic consequences to man and
> machine?
We plotted the composition and amount of the accumulating metals in the
oil as the components aged. When the unit from which the oil samples
were taken showed a spike on our charts, we had the maintenance section
pull the transmission. Tear down of the component provided the proof of
the pudding.
>
>> Tough little engine. I never saw a 1.9L with a rod through the engine
>> case.
>> But I have seen plenty old air cooled engines and 2.1L WBX engines
>> with the
>> rod and hole through the block. The 1.9 L engine uses a fixed length
>> bolt
>> with no stretch on the rods. The 2.1L WBX uses a stretch bolt for the
>> rod
>> end. Problem is the stretch bolts just keep on stretching. This allow
>> over
>> time for the rod end bearings to wear to oval, lose oil pressure, and
>> seize, throwing a rod amd destroying the block. Good rebuilders like Bob
>> Donalds use the 1.9L bolts in rebuilding a 2.1L engine.
>
>
> That went just a little over my head. Mind explaining with a little more
> elaboration? Bolts that are made to stretch?
Stretch bolts are often used in industry. When a given procedure for
installation and a specified torque is applied, the bolts, being
designed to stretch, then achieve the required engineering
specification. In the case of the 2.1L WBX, it is a weakness in the
original engine design The rod assembly components specifications could
have been better. More stout or robust bolts could have been specified
and used. Bob Donalds had a lot to say about this on his web site at
www.bostonengines.com.
BTW, in radial engines in aircraft, the crankshaft has a single crank
throw, and a single rod, the master rod, mounts to it, with all the
other rods mounting on the master rod. The master rod is the only rod
in the engine whose Crank end travels in a true circle. All the other
rods, being attached to the master rod, travel in an ellipse. It's a
marvel in engineering. Anyway, because all the other rods mount to the
master rod, the master rod is one piece. The crankshaft is in two
pieces. The crank shaft parts are clamped together, and the bolts that
hold them are stretch bolts. Once the bolts are installed and the
torque applied, the bolt length must be measured with a micrometer and
have stretched to a specified length. If it has not, then the bolt must
be replaced. If the stretched length for the specified torque is to
much, then the bolt must be replaced. It's a heck of a thing. The
stretch bolts used in this particular application are extremely
expensive as they must be engineered and manufactured to perfect
tolerances.
> Off to camp at Guadalupe state park this weekend. I hope to hell that
> the van makes it there and back. Had a couple of maintanence items I
> wasn't
> able to tackle (afford) before we leave.
Have a good trip!!
Regards,
John Rodgers
88 GL Driver
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