The pilot reported that, during an agricultural application pass, the elevator control felt abnormal. He chose to return to the airport and noted that the elevator control was unresponsive.
He attempted to maintain pitch control by using the elevator trim, but turbulence made this difficult.
During the off-field landing near Brickeys, Arkansas, the Air Tractor’s nose pitched down. The pilot countered with nose-up trim, and the airplane stalled and then hit the ground, which resulted in minor damage to the propeller.
A post-incident examination revealed that the attachment hardware, including the bolt and nut, at the elevator pushrod had separated. Maintenance had been performed on the elevator control pushrod about 20 hours before the flight, and the bolt and nut would have been removed and reinstalled during this maintenance.
It is likely that maintenance personnel did not properly reinstall the attachment hardware after performing the maintenance.
The NTSB determined the probable cause as the in-flight separation of the attachment hardware at the elevator control pushrod due to maintenance personnel’s improper reinstallation of the attachment hardware.
NTSB Identification: CEN15IA200
This April 2015 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.
RII – whether large or small aircraft it is a good practice on any control surface or critical system work.
It always helps to go back and look over the work you completed or have someone else re-inspect the work done.
As an A&P, any time I do critical work I make it a point to walk away from it and come back later OR — preferably — come back the next day with “fresh” eyes. And … just to be sure … I go back when the entire job is complete and do one last check. I feel this is better than having a second set of eyes because I know what I did but … a second person is another way to accomplish the same end goal. Not every task is a critical task so it doesn’t take long to do this.
That nut on that bolt probably was supposed to have a cotter pin installed to prevent that from happening so that was where the mechanic went wrong. What is not clear from the report is where in the control system this bolt was located and whether it could have been observed during a proper preflight inspection. That was one of the little details that my instructor taught me to look for, cotter pins on control system bolts and in the ends of piano hinges which retain the rod (Cessna ailerons).
What happens to the erring mechanic? Is there a suspension?
Quite possibly, or a re-examination. Mechanics are invisible until something goes wrong and then the wrath of the NTSB,FAA and the pilot gods is upon them.
We are very aware that many lives depend on our work and yes we sometimes make mistakes. Do try and remember this however, when you are flying and the “hero” of the public eye, “So when you see mighty jet aircraft
as they mark their way through the air,
Remember the grease-stained man with the wrench in his hand;
he’s the man who put them there.” From the “Forgotten Mechanic”
I’ve been told the most dangerous flight is the one immediately following PM.
BJS,
You are very correct.!! Any time my aircraft is worked on, by me or other A&Ps, I treat it as a post -maint. test flight. So, on the 1st flight, I remain in the pattern or within gliding distance to the airport.
There are at least 3 types of nuts used – locking, castleated [needs a cotter pin or safety wire ], and a nylock. Each has limits on where it can be used.