New Cylinder AD's released by FAA
 

Well let's see how long this thread lasts. :ugh:

Warning: Disclaimer below needs to be understood
Links below are to another forum.
Links below do have the potential to cause advertising an education source, an Airworthiness Directive, and possibly a parts manufacturer (although it looks like bad press for them).
Links below are to a website run by a not for profit society, but no doubt they do try to run with a surplus to further their cause and pay some employees who run it.
The second link even contains a link to a popular Aviation Web based commercial for profit news outlet.

https://bonanza.org/forums/index.php?topic=101005.0

https://bonanza.org/forums/index.php...253#msg5003253

This could well affect some private TCM powered aircraft owners in Australia.

why don't you post a link to the actual FAA airworthiness directive ?

Coz that is not where I found it nor is there any good detailed story to go with it.

:rolleyes:

Interesting problem. Notwithstanding obvious issues of dissimilar metal expansion rates....why would there be changes in metallurgy of a proven process?...and the robustness of a "screw" fit at the junction of head and barrel...why would this assy separate?

Jaba, are there any further clues? Corrosion? Fretting? Stress risers?

Folks,
I sometimes wonder if this is the FAA acting like CASA.

AOPA USA has done considerable research on this issue for the members, the results were interesting, particularly as (if I am remembering correctly, FAA did not do a cost/benefit analysis) AOPA figures showed the failure rate of OEM cylinders to be worse.

I think there is a definite element of: "I'm from the Government, and I am here to help, whether you want help or not".

Tootle pip!!

This is not new. It is the most recent result of an ongoing issue that's been around for quite a number of years. Some of us who have been following this are a bit surprised it took so long to finalize. The issue was identified almost a decade ago. It's old news.

The screw threads do not hold the head on the cylinder. That is accomplished by an interference fit between the head and the cylinder. That is where the issue has been. If the screw threads were the front line of defense on holding the heads on, all of the heads would be departing the cylinders!

Run that one past again Walter, didn't get a rope on it

This will be interesting!!

This should enlighten a few Pruners. If train wheel outer tyres stay on using this principle so should cylinder heads.

http://www.eci.aero/pdf/SeparationAn...essnaPilot.pdf

Cheers RA

^^^^^^ And before that, many a Wells-Fargo stagecoach completed it's journey on wooden wheels, with shrunk-on steel tyres.!

Wooden barrells also rely on the steel hoops to hold the staves tightly -enough together , that the barrell is fluid-tight.

There's nowt much new in engineering,just the knowledge falls into disuse when an alternative technology becomes more suitable for purpose, for a while.

As an aside, underfloor Central -heating is now the "in" high-efficiency heating-method........WELL! fancy that! the Romans had it a few THOUSAND YEARS AGO.

A great piece of research, nevertheless....about time the US Pilots started a class action against the legislators, for dereliction of duty, unfitness for purpose and Commercial bias against the aftermarket manufacturers.

The latter is irrefutable....they are imposing sanctions against the most reliable products, whilst leaving the statistically least-reliable OEM product untouched.

Dare I ask if $$$$$$$$$ might be changing hands. Calculate what it would be worth to the remaining players if a major competitor was knocked out of the ring. How much were cylinders before a bit of genuine competition came on the scene? Is this what is meant by the current popular term " Government- Business Partnership "
RA

If something stinks, there's usually a reason......something rotten somewhere?

Problem for Australia is that there may be no one with sufficient time, expertise and objectivity in the regulator to properly analyse the data and refuse to adopt this AD verbatim.

As usual, owners will have to pay to address a remote risk that is patently clearly not of their making and, more bizarrely, is patently clearly a more remote risk than the failure of the OEM’s product. All in the name of ‘safety’. :yuk:

Something rotten..... In Denmark?
Cracks at to the screw thread are not new as Walter has said.
How many cylinders in Aust are affected?

If the AD comes out it is auto on our system. Yes oem cly cracked but let's compare apples to apples. Ie hours to hours. The older the cly the more likely it is to crack. So are these 1st service life cly that are failing or second or 3 rd time around the block. If they are 1st then not hard to see why the looking at them careful. Funny that is why we do a leak rate check one of the things we also look for but some think a leak rate is not relevant
Cheers

CASA has discretion:

Casa won't go against another country's AD. They will not do it for litagation
Cheers

Sadly, I think you are correct. The GA sector in Australia doesn’t have sufficiently united brains or brawn to make CASA exercise its powers on the basis of objective data.

(PS: Great to see the incredible improvement in your usage of apostrophes, yr right. ;) )

Creampuff,
You may remember the Bell47 Main Rotor grips that were downgraded to 1200 hour life. In Australia we convinced CASA that an eddy current inspection of the threads allowed us to retain the original hour timex.
So it has been done before