According to the student pilot, they performed a preflight inspection of the Cessna 172 with no anomalies noted. They departed Gwinnett County Airport (KLZU) in Lawrenceville, Georgia, and flew to Barrow County Airport (KWDR) in Winder, Georgia, and performed several circuits in the traffic pattern.
While on the final approach leg of the traffic pattern to Runway 31, the student pilot turned the yoke to the right “and felt it give as if a cable had become detached.”
The flight instructor took control of the airplane and experienced the same effects; the yoke could be turned in a “complete circle with no response” from the airplane.
The airplane veered to the right and descended into trees.
The airplane came to rest about ½-mile from the approach end of Runway 31 in a wooded area.
A post-impact fire consumed the fuselage and wings.
Examination of the airplane revealed that flight control continuity was established from the cockpit to the elevator and rudder.
A review of the aileron control system revealed that the right direct aileron control cable was attached to the control yoke turnbuckle, but was separated in the area near the the control yoke pulleys under the cockpit floor. No other anomalies were noted with the airplane.
The aileron control cable was removed from the airplane and sent to the National Transportation Safety Board Materials Laboratory for examination. Examination of the cable revealed that about 10 wires that were elongated past the fracture surface exhibited erratic deformation directions. These wires exhibited angled fracture surfaces, or localized necking near the fractures. About half of the other broken wires, particularly in the core, exhibited flat surfaces with smearing or wear lines. The direction of these smearing lines was consistent across multiple wires. Furthermore, several wires exhibited features consistent with a tensile overstress fracture.
On Aug. 17, 2021, at an aircraft total time of 24,420 flight hours, an entry in the airframe maintenance log indicated that the right inboard flap support rib was cracked. At that time, it was noted “disconnected right aileron and flap control cables…re-connected control cables using new hardware, and set cable tensions to manufacturers specified limits.”
A review of the airframe maintenance log revealed that between Feb. 2, 2021, at an aircraft total time of 24,054.7 hours, and the date of the accident, there were 9 entries in the maintenance logbook that stated “completed a 100 hour inspection IAW [in accordance with] MM [maintenance manual].”
Furthermore, all entries stated that the “aircraft has been inspected in accordance with a 100 hour inspection IAW FAR 43 appendix D and maintenance manual and is approved for return to service.”
The aircraft total time at the time of the accident was 24,830 hours.
According to Appendix D to Part 43, “Each person performing an annual or 100-hour inspection shall inspect (where applicable)…flight and engine controls for improper installation and improper operation.”
According to the Cessna 172 Maintenance Manual, during each 100-hour inspection, “Aileron structure, control rods, hinges, balance weights, bellcranks, linkage, bolts, pulleys, and pulley brackets — check condition, operation and security of attachment.”
Furthermore, the 200-hour inspection lists “Ailerons and cables — Check operation and security of stops. Check cables for tension, routing, fraying, corrosion, and turnbuckle safety. Check travel if cable tension requires adjustment or if stops are damaged. Check fairleads and rub strips for condition.”
Probable Cause: Maintenance personnel’s failure to detect the damaged aileron cable during the most recent inspections, which resulted in the separation of the aileron control cable and subsequent loss of airplane control.
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This March 2022 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.
Sounds to me like problem originated from a binding / frozen cable pulley. Individual cable wires with “FLAT SURFACES and SMEARING” are indications that the cables were rubbing across a stuck pulley for a very LONG TIME; eventually reducing their cross-sectional area and weakening them to the point where tensile fracture occurred.
During annual inspection, EVERY flight control cable pulley needs to be checked for binding. Proper examination often needs to be performed through a small inspection plate opening BY FEEL. In addition, look for flat spotting of cable wires shortly before and after each cable pulley with a strong flashlight.
My technique for verifying cable pulley bearings are good through an inspection plate is to LIFT the cable from the pulley with one finger and spin pulley using other fingers. Because of cable tension, this method only works well when pulleys are not accomplishing much in the way of a directional change of the cable, but instead are used more for guidance as they are in much of the control systems of my 172. Pulleys providing ~ 90 degrees of cable directional change need to be closely observed while someone else is moving the controls; again, closely examining cable wires at either side of the pulley. A single broken wire strand sticking out of a cable IS A BIG CLUE that you NEED TO LOOK DEEPER.
Jerry King
Sounds like elevator was connected properly, along with the rudder. Only the ailerons were unusable…
absolutely no reason for this.
I guess they both lived. Hard to belive looking at the wreakage.
Leigh Smith can be contacted at techflying.com
My commercial training was at National Aviation Academy when they had a flight school. On “fun days”, building time, we would practice maneuvers simulating control loss. In neutral trim and with fuel tanks balanced, controlled flight was practiced using power and having the rear seat passenger shift from side to side as one exercise. Another tactic of instructors was that they would pull out these 3″ suction things and put them on 4 or 5 instruments and then we would complete instrument approaches. Being prepared for failures, mechanical or electronic, needs to be a part of thinking and training, and it is “fun” when you don’t have the panic of real failure in a bad situation.
Leigh Smith,
Where are you located? I would like to get some instruction from you!! At 600 + hours its
perfect timing.
If a 172 is properly trimmed it will recover from almost any atitude by releasing the controls and maintaining a straight line with the rudder. Leigh Smith is right, there was no need for this accident.
So tired of the poor training that takes place. There was no reason for this crash, had the pilot been trained properly! If you fly with me you will fly the whole pattern without touching the yoke or stick! With rudders, trim and power you can land the plane safely! Also if you fly with me, you will have no instruments, pitch and power is airspeed.
Need to get back to basics instead of button pushing. Your feet can do so much yet most pilots don’t know what they are for.
Yup.!! Rudder and trim can be used to fly the aircraft.!
I’ve flown the EAA Ford Tri-motor. In order to start a turn, the pilot puts in full rudder. When the aircraft starts to roll , then aileron can be added. Otherwise, due the the very high adverse yaw, putting in aileron will make the aircraft yaw opposite and not turn.!!
Right on Leigh!
There is a domino effect. Students with no stick and rudder skills are being “trained” by young instructors also posessing little to no stick and rudder skills.
They have become superior computer programmers (glass cockpits) while severely lacking in the knowledge of basic aerodynamics.
My suggestions:
1.Every student and instructor should be required to read the bible– “Stick and Rudder” by Wolfgang Langewiesche which was published decades ago. Still available in print through Amazon. The audio CD version is available for those who find that holding up a book is completely foreign to them!
2. Train in something simple like a Piper J3 Cub. It consists of engine instruments, a wet compass, mixture, carb heat, stick, rudder and trim. That’s it—not even an electrical system or vacuum pump system to power instruments that are simply not there. Look out the windshield and use God’s gift–a NATURAL horizon. While doing this, SCAN for traffic with natural EYESIGHT rather than ADSB which won’t work without an electrical system in the first place.
3. Spin training. Students and instructors will learn what rudder is all about and discover that it is the most essential flight surface to maintain smooth, coordinated and efficient flight.
4.Tailwheel training—DITTO. “Driving” a tricycle gear airplane onto the runway and feeling the aura of success will become a wakeup call when they have to land a taildragger with the simple utilization of pitch, power, trim and RUDDER.
5. Initial solo will be restricted to students utilizing a tail dragger who have shown proficiency in such aircraft. Cross country training will not begin until the student has mastered the taildragger.
Wow..!!, nearly 25,000 hours on a 1981 Cessna. That’s an average of 600 hours a year.!
With the hot , humid weather in the Atlanta area, and what appears to be aircraft that are tied-down on the ramp, noting where the flight school is located, moisture appears to have corroded the cables.
Also the re-tensioning of the aileron and flap cables may have been set to high, putting excess tension in the cable. ?
This area is difficult to inspect. I know since I’ve had to remove 2 panels and the carpet over the ‘tunnel’ area. My C175 has Johnson bar flaps, so the mechanism and cables limit the view in the ‘belly’.
I hope that the flight school has inspected the cables on their other aircraft ?