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Cyclic Hotline
20th Dec 2001, 09:31
This story appeared in the Boston Globe yesterday, regarding an accident that occurred a few years ago. The information is pretty sound, there is a history of problems with these parts.

We install a secondary spring to all our C206 throttles, to ensure that in the event of a linkage failure it will to full throttle.

Thought it might be of interest to anyone unfamiliar with the history of this installation.

<a href="http://http://www.boston.com/dailyglobe2/353/nation/Defect_puts_many_small_planes_at_risk+.shtml" target="_blank">Boston Globe story</a>

greybeard
23rd Dec 2001, 04:06
Can't open the link.

Was a victim of the fault in 1966 in what would appear to be a similar problem.

Any more links to the site please.

I cant beleive it still happens.

<img src="mad.gif" border="0">

Cyclic Hotline
24th Dec 2001, 00:47
Apologies for that bad link. The Boston Globe immediately archives it (apparently) and charges $2.50 to retrive it. It was a long (4000 word article) so I didn't post it in its entirety. I normally post stories rather than links for this very reason!

The NTSB accident report is <a href="http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001208X06649&key=1" target="_blank">here.</a>

Here is a wire story version.

Wednesday December 19 2:57 PM ET
Report: Part Blamed for Crashes

BOSTON (AP) - Excessive wear on a throttle linkage part has been blamed for more than a dozen crashes or forced landings of older Cessna planes, The Boston Globe reported Wednesday.

In the most serious crash blamed on the throttle control arm, a Cessna 200 lost power and crashed during a sightseeing flight in Alaska in 1996, killing the pilot and two passengers, the newspaper reported, citing federal records. Cessna stopped using engines with the part in 1992.

Over the last decade, pilots and some of the Federal Aviation Administration's own inspectors have urged the agency to issue an order fixing the problem, the Globe reported.

However, FAA spokeswoman Laura Brown said the agency believes poor maintenance, rather than design problems, leads to rapid wear of the part, which is made of bronze rather than more durable steel.

The FAA, Cessna and Teledyne Continental Motors - which made engines for Cessna planes before 1992 - have all urged pilots and mechanics to make frequent checks of the part in older Cessnas.

Cessna officials say more than 1,000 of their aircraft built before 1996 have the part, and Teledyne officials said they have produced about 175,000 engines in the last 50 years with bronze throttle arms.

When Providence, R.I.-based Textron bought Cessna in 1992 for $600 million, it switched to using only Textron Lycoming engines, which uses steel linkage parts.

Cessna and Teledyne have blamed each other for the bronze throttle arm's tendency to wear quickly.

More than a year before the Alaska crash, Cessna urged Teledyne to make the arm out of steel, but the request went unheeded, the Globe said. Cessna officials refused to comment.

Teledyne said any wear was due to Cessna's design of the linkage, adding that some mechanics servicing the thousands of engines in the field were to blame for not making certain that connections were tight, the newspaper said.

John Barton, chief technology officer for Teledyne Continental Motors, said the arm cannot wear if its connection is properly tightened.

At least 25 failures of the throttle arm have been reported to the FAA since 1975, according to the Globe. Some were discovered in routine maintenance. However, at least 15 times before the fatal Alaska crash - and twice since - planes were forced to make emergency landings because of failure of the throttle arm, the newspaper said, quoting voluntary reports to the FAA.

Both the FAA and the National Transportation Safety Board found that the failure of the part caused the Alaska crash.

The families of those killed in the Alaska crash received six-figure settlements from the companies last year.

NdekePilot
27th Dec 2001, 02:21
About 7 years ago, flying a Beech Baron 58, I noticed in the descent the manifold pressure gradually increasing despite reducing the throttles the usual 1" man. press. per 1000ft. Brought the throttle/power lever back all the way to see, and found that it was no longer connected to the linkage, and that the engine had gone to full throttle as the linkage was spring loaded that way. I turned around and returned to Lusaka and landed using the mixture to roughly control power until touchdown when I pulled the mixture to ICO.
A couple of years later, two friends returning to Lusaka in a Cessna 206 had exactly the same problem, however, in this case the engine went to idle as an AD had been issued requiring removal of the spring so that the engine would not go to full power. Fortunately for the pair, they managed to land the aircraft on a busy main road (the only flat space around) and miss everything except a telephone cable which snapped, with no damage to themselves or the many onlookers.
Apparently, an a/c in the US had gone to full power after the linkage broke and crashed because the pilot was unable to land the aircraft in this state, although I can't guarantee the truth of this event. This prompted the AD.
Having had first hand experience of this particular problem, I know which way I personally would like the linkage to go in the case of a breakage. I can't see the "safety" in having an otherwise perfect engine going to idle. We don't all fly over flat, uninhabited farmland!!