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.
CFI’s Narrative
I was conducting flight training in a Kitfox. During the takeoff we went off the side of the runway and into the grass. No damage to the aircraft occurred.
Prior to the incident we did our normal checks for takeoff and everything was fine.
Specifically during run-up I had the student do a control check and, even later, having not noticed the initial control check, I asked to see another and the student responded with another control check.
Upon takeoff the aircraft was under control but later got out of control and went off the right hand side of the runway.
After initial liftoff, the aircraft stalled and resettled back onto the runway. During the next liftoff I pushed the stick forward to prevent the stall and off we went. I took over the controls and noticed the ailerons were not normal. They had stiffened significantly and would lock in a position.
So, we requested priority handling and came back for a fairly non-eventful landing.
After further inspection upon shutdown, the seats themselves were cracked and were pressing onto the physical cables of the ailerons. The controls weren’t able to be moved without major physical input. The seats were written up for repair and we went home a bit shaken over the whole thing.
As far as why the aircraft went off the side of the runway: I think the student was in utter shock at the stick being stiff and lack of communication and reaction on my end lead to a loss of control of the tailwheel aircraft. By the time the aircraft was off the side of the runway, we had control but found ourselves in the grass. From there, we opted a departure was the best way.
Student’s Narrative
Arrived to complete additional tailwheel flight training in new Kitfox Model V with CFI. Performed a complete pre-flight inspection prior to start and performed an after start check of flight controls prior to taxi in accordance with aircraft checklist.
Performed run-up and system check. Requested taxi clearance and taxied to hold short line. While waiting for departure, performed another control check while waiting for other airplanes to depart, we found no issue with the aileron/rudder box control check. Received clearance onto the runway and applied full power for takeoff.
After raising the tail and beginning the rotation, the control stick seemed to be jammed. The airplane began departing from the runway to the west (light winds out of east) and couldn’t effectively aileron into the wind to correct. After lift off the control stick was jammed but could be forced through the stuck position.
We requested priority handling and proceeded to evaluate our best course of action to return for landing. We made a turn to the east for left pattern and communicated to Tower’s question that no further assist was needed on the ground as we had moderate control of the aircraft. Tower gave us clearance to land and we proceeded to make a normal landing and taxied to Taxiway 1 to vacate the runway.
After exiting the runway, we taxied back to the hangars for parking.
Upon evaluation of the aircraft we found the fiberglass seat had broken and sunk into the control cables under the seat pan. This inhibited their freedom of movement. No other obstruction or malfunction was determined.
Primary Problem: Aircraft
ACN: 1988269
A kitfox does not have “control cables” for either the alierons (more correctly flaperons) or elevator. Both functions utilize push/pull tubes and rod ends. It has control cables for the rudder but that its all.
What has happened is the seat came down on the push pull tube on port side of the cabin, blocking the roll control push pull tube. The Elevator PP tube runs down the middle on the bottom of the fuselage and is pretty well protected.
Builders have fashioned a couple solutions to this early design anomoly, either affixing a “butt block” to the cabin floor on the port side to create a protective channel for the push pull tubes; or, adding the available aftermarket factory designed under seat storage bins which totally protect the controls from a seat collapse and adds some nice storage space. The current Kitfox seats have integral storage bins cast into the seat structure.
The scenario is not unheard of with the earlier seats if modifications have not been made; and, the problem can be initiated by a builder not following the build manual such as just allowing the seat pan to rest in position without fastening it down.
Current kitfox design has a seat designed to prevent this in case of a seat cracking; and, the seat now bolts down securely to the fuselage structure. FYI – the seat does not move for pilot adjustments, the rudder pedals adjust to accomodate pilots of different heights.