This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
Technician replaced the defective carburetor heat control cable in the Cessna 152 with a new FAA approved cable.
During removal of the old carburetor heat control cable, the nut attaching the cable housing to the instrument panel was lost and eventually became lodged in the elevator trim control wheel sprocket and chain.
During the next training flight, the pilot/student attempted to apply nose up and nose down trim and it was discovered that the trim wheel was jammed.
The flight crew further moved the trim wheel to the point where the trim “just gave” and “slipped” and the aircraft was forced into a stuck extreme nose down trim configuration.
The flight crew performed a turn back and performed a successful landing.
Upon further inspection the cable attach nut was found lodged between the sprocket and chain. The sprocket and chain were inspected for damage and system rigging checks were performed with no defects noted.
We believe the cause of this incident was human error by the inaction of the technician to retrieve the missing nut. Despite previously loosening the nut and installing a new cable with a new nut, the technician either forgot to find the missing nut or did not hear it fall in the trim components.
Primary Problem: Human Factors
ACN: 2032553
Hard to grasp why the mechanic let this slide. USAF jet mechanics are constantly taught to stop maintenance until the misplaced hardware or tool is retrieved. The mechanic needs to get his A&P suspended. This is intolerable. Wish I would have gotten my A&P license.
Ex F-15 Crew Chief
A&P IA here I agree it is tough when something is dropped or missing tools but a mechanic needs to hunt till you find it and I have had to do this a few times and always feel good when the item is found
Always double check the mechanics work. Be your own I.A.
3000 hours
Cessna SEL
ATP/ A&P/ I.A.
I am retired now after over 40 years in the biz jet world. My first 20 or so was touch labor as an avionics tech.
I learned early on that any hardware dropped in a cockpit will almost always find the opening by the rudder pedals. With schedule pressure, the task of pulling floor panels and possibly even crew seats, it was always tempting to let it go. But I didn’t.
We (collectively) have to be aware of the potential harm of our oversight.
I was an avionics tech in Wichita. This subject,was the most concerning of all because its a stupid mistake,i hate feeling stupid especialy if you add killing a family.I was blessed to get out with a stellar record.Now im an A.A.T.D. flight simulator producer,i never would have had this oppertunity if i had got busted for a stupid mistake.
Plenty of blame to go around here. Jammed trim control was merely annoying until it was forced into bad position.
When you encounter a jammed control that doesn’t immediately affect flight such as this trim wheel, land.
The crew of the Super 80 that kept screwing with their trim until it completely broke and killed everyone was abeam LAX and should have gone there with what was a out of trim but controllable airplane.
One of my favorite bucking bars was found under the rudder pedals of a brand new C 172. I reported it to a Cessna field service manager (formerly my boss) and he asked me if we were invoiced for it. Some time later I was talking to him about a 152 on which we couldn’t seem to alleviate a right wing heaviness. He retorted, “Remember that bucking bar we never charged you for? Wrap it in paper and stuff it in the right wingtip.” Of course he was kidding. We did finally fix the wing heaviness. That’s another story.
Air Fact ran this article about 5 years ago written by me. It was the closest I came to having a fatal accident in aircraft. The elevator failure was serious and luck/ God and calm winds and being calm were the only reason the aircraft was controllable and landed successfully
I asked the FAA for an AD to change this system attaching the elevator to the horizontal stabilizer. They only responded after 4 year. to refer to a Special Airworthiness Information Bulletin. SAIB…..It took an amazing 3.5 years to close the case and I was exonerated from any cause of this accident. I was being investigated for missing it on the preflight inspection……The CFI is the PIC and responsible for it all. The Annual could have caught it but it did not?…..
Again I am publishing this article here to make Cessna 150 owners aware of this and those that own this aircraft from 1959-1970. Check with your A&P and have the attaching system changed to the recommendation by me to the FAA.
The NTSB accident report is also attached at the end of the article with pictures and recommendation. The NTSB did a great job investigating and reporting the cause……
ELEVATOR FAILURE AT 4500 FEET
https://airfactsjournal.com/author/richwyeroski/
Thanks You
Good example of poor maintenance practices by a mechanic. Anytime any hardware (or tool) is dropped, it MUST be located. The mechanic should have known he dropped the nut since he had to replace with a new one. Could have been a serious accident.
Go with Fuel Injection and you won’t have to worry about a carburetor heat control cable.
Something similar happened to me with a one year old 1976 Cessna 310R. Twice, on approach, the ailerons locked up, then with force would break loose and operate normally. Twice, I opened up both wings, removed the forward seats and floorboards, and crawled under the instrument panel like a contortionist looking for the cause, and could never find anything. I even used a mirror and flashlight to look at the sprockets and chains inside the metal-enclosed vertical sections of the yokes….nothing.
When this happened a third time, I removed the glare shield from the instrument panel and jammed my head under the windshield to try to get a better look. And lo and behold, there it was! At the Wichita factory, someone had dropped a 90 degree pneumatic fitting while plumbing the instruments, and obviously could never find it. It had landed in the opening atop the pilot’s vertical yoke section, was hidden from view by the metal surround, had worked its way down beside the aileron control sprocket and chain and would momentarily jam the sprocket!
“Trust but veryfy.” Seems to me with the numerous accounts of incompetent airplane mechanics across the Fruited Plain, it would be prudent for owners to shadow the mechanics while they do their work. If they don’t like it, go to another shop. Nothing is worth death by airplane.
/J
If you have to shadow your mechanic, you are using the wrong shop.
Discipline please…it matters.
Was this technician a former Boeing employee??
Probably not a former Boeing employee. If that had been the case, there probably wouldn’t have been a nut on it in the first place.
now that’s sad, but funny!