The commercial pilot was conducting a cross-country personal flight in the Cirrus SR-22. He reported that, during cruise flight, the airspeed began to decrease, and the engine began to lose power.
He attempted to restore engine power, but was not successful. He then conducted a forced landing to a road in Langola Township in Minnesota.
During the landing roll, he maneuvered the plane to miss an oncoming car, and the plane subsequently struck a guy wire, which resulted in substantial damage to the left wing.
A post-accident examination of the engine revealed that the throttle control lever nut was not torqued to factory specifications in accordance with an engine manufacturer service bulletin (SB).
The knurl teeth of both the throttle control lever and shaft displayed signatures of machining with adhesive wear scars on the surfaces.
In addition, the surface of the control lever that the nut was normally secured to displayed scoring wear scars. The surface signatures were consistent with the throttle control lever nut not having been properly torqued.
A review of the engine logbook entries revealed that a rebuilt engine was installed on the airplane about 73.1 flight hours before the accident. The mechanics at the repair station who installed the engine, which would have included installing the throttle body and torqueing the throttle control lever nut, reported that they were knowledgeable of the manufacturer SB, and no discrepancies in their procedures were found.
Even though the mechanics reported that they were familiar with the SB, it is likely that they did not apply sufficient torque on the throttle control lever nut during the installation of the engine.
The NTSB determined the probable cause as maintenance personnel’s failure to apply sufficient torque on the throttle control lever nut, which resulted in a loss of throttle control and subsequent loss of engine power.
NTSB Identification: CEN14LA486
This September 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Quick to blame the mechanic(s)? The report stated the maintenance personnel were knowledgeable of the manufacturer’s SB, and no discrepancies were found in their procedures. Still, the NTSB jumped to a conclusion that it was “likely that they didn’t apply sufficient torque” and the “NTSB determined the probable cause as maintenance personnel’s failure to apply sufficient torque….”
The NTSB first stated the mechanics were knowledgeable, and no discrepancies were found in the procedures, then they turned around and blamed the mechanics and you piled on.
How many times do we think it is unfair to the pilot to blame the incident/accident on pilot error?
What if the procedures in the manufacturer’s SB are inadequate, wouldn’t you want to have that examined since there appears to be a disconnect in the report and the conclusion?
Under Part 43, pilots can do a lot of maintenance. Three of you could go on and get your A&P, so we would have three more good mechanics out there.
Question for the IA and A&P out there: why in the world of common sense would a bolt and nut combination this critical to safety rely on torque or even a lock washer combination to keep such a small bolt nut combination secure. this looks like a prime location for castle nut and cotter key or a self locking nut at a minimum. Perhaps with tolerance for heat as opposed to a nylock nut. I look over many aerobatic aircraft each year prior to competitions, many of which are experimental category, and almost the entire fleet have the throttle and or mixture control set up with this small safety item. On certificated aircraft it was my thought that there was a requirement to have throttle advance to WOT in the event of cable or attachment arm failure. Boats have a similar feature but there a spring retards the throttle in such an event.
Interesting. I attempted to post a comment with name and email in the required fields, and I get this message from the website: “Your email address will not be published. Required fields are marked *”
I’ve published before with this name (still mine) and email (also still mine). Software glitch??? New policy??? Que’ pasa?
20% of all accidents involving GA aircraft have a maintenance root cause (from NTSB data base). Half are errors of commission, omission, or erroneous information. (From Mike Busch, prolific author of GA maintenance topics). Mechanics are human, which means we need to be as vigilant about a SOLID pre-flight inspection of everything, every time we fly as we are about our own health and our own decision making.
I know most pilots I talk with would hope it ain’t true, but pilot incapacitation or just plain rotten decision making are the cause of the other 80% of aircraft accidents… and they are all PILOT controlled risk factors. 🙁
Don’t point the fingers too harshly guys, since when you point one (20%) the other four (80%) point toward ‘Yours truly’. 🙁 So very sad.
This is why I get involved in the maintenance of my aircraft.
I see pilots all the time that just toss the keys to the mechanic and walk away and never look at anything.
Now I know not everyone is mechanically inclined but good grief if you aren’t and you are a pilot you need to at least try to gain a little knowledge.
This event was not something you would see on a cursory walk around but a loose oil cap or gas cap or low tire or brake fluid leak IS.
So I am just encouraging people to get involved to some degree.
You have to be so vigilant with you maintenance providers. They are on the ground, you are not! I have seen some shortcuts taken and downright lies about work performed. I always check and if in doubt, change providers.
A couple of years ago having gone thru the bueaurcratic nonsense of renewing my third class medical, and going thru all procedures to get current I had two occurrences of mechanical failures on rental aircraft that left me totally discouraged. After reading this article I am not the least encouraged by the poor state of aircraft maintenance throughout the country.
My two occurrences involved two different aircraft, one a Cessna 172, the other a Piper Arrow both rented from the same FBO. Both involved cable linkages. In the case of the Cessna it was the carb heat, and the Piper was the alternate air. As we taxied out to the run up area on pulling the carb heat to check the handle came out about a foot along with the cable. A few days later during a winter flight to the Hudson River in New York in the Piper Arrow having received a popup IFR clearance in light snow on the return trip the engine began running rough. Later we began having difficulty maintaining altitude. We informed ATC and requested vectors to the nearest suitable airport. By the time we landed the plane was shaking violently. Turns out the next day their mechanic said the alternate air cable came undone and the air filter was clogged with packed ice and snow. So the alternate air did not function. And now I see your article involving another cable that results in a forced landing. Just curious, what is one to think about the state of maintenance in aviation? Something more needs to be done. What do you all think?