According to airport security video, the Cessna 172P departed Runway 4 at Palm Beach County Park Airport (KLNA) in Lake Worth, Florida, on a training flight.
It rotated and began to climb, descended, and began to climb again. The airplane then rolled right until it was in an approximate 90° right bank and continued in a right descending turn until it hit the ground.
The CFI and student pilot were killed in the crash.
A pilot who witnessed the accident reported that the airplane’s engine “sounded like it was full throttle the entire time.”
The airplane hit the ground about 200 feet from Runway 16/34. The debris path was oriented on a 006° heading and the airplane came to rest about 140 feet from the initial impact point at an elevation of 16 feet mean sea level (MSL).
All major components of the airplane were located within the vicinity of the main wreckage.
The engine remained partially attached to the fuselage through the engine mounts.
Crankshaft and valvetrain continuity were confirmed by rotating the crankshaft by turning the vacuum pump drive gear.
Compression was confirmed on all cylinders. The cylinders were examined with a lighted borescope and no anomalies were noted. The magnetos were rotated by hand and produced spark on all leads. The carburetor was examined and no anomalies were noted. No debris was noted in the oil filter or the oil pickup screen. There were no anomalies found with the engine that would have precluded normal operation.
The fixed-pitch propeller remained attached to the crankshaft flange and the two blades remained attached to the hub. One propeller blade was bent forward about mid-span and exhibited chordwise scratching and the other propeller blade was twisted and exhibited chordwise scratching.
The cockpit was crushed in the impact and multiple instruments separated from the panel and were damaged.
The empennage remained partially attached to the fuselage. Elevator and rudder control continuity were confirmed from the flight control surfaces to the flight control yoke in the cockpit.
The left wing was separated from the fuselage. The outboard 6-foot section of the left wing was crushed aft and the wing tip was separated and located along the debris field.
The right wing also was separated from the fuselage. The outboard 5-foot section of the wing tip was bent in the positive direction and crushed aft. The wing tip was separated from the right wing and located along the debris path. The right wing tip light lens cap was located at the initial impact point.
Aileron control continuity was not confirmed.
A separation was noted in the aileron control system in the vicinity of the left upper door post right direct aileron cable pulley.
The pulley was removed, examined, and exhibited corrosion. The pulley did not move freely. The right upper door post left direct aileron over pulley was removed and examined. The pulley did not rotate freely and corrosion was noted. Several other breaks noted in the aileron control system were consistent with tension overload failures.
Examination of the aileron control cables at the NTSB Materials Laboratory revealed that several wires exhibited uneven, localized thinning either at the separated ends or along the length of the wire.
Pockmarks consistent with corrosive attack were observed on the surfaces of numerous wires. Some of the wire ends had necked down, with cup-cone fractures visible, while other wires had no thinning and angled fractures at the ends. The cable ends tapered to points and localized thinning of wires and shedding of material was noted, as well as pockmarks.
The woody appearance of the cables, the shedding of material, and the pockmarks were consistent with a corrosive attack. Angled fracture surfaces were noted on some wires that also exhibited a woody appearance. Cup-cone fractures were noted on necked-down wires that had dimpled features consistent with ductile tensile overstress.
According to the owner of the flight school, the airplane was purchased on May 4, 2023, just weeks before the May 26, 2023, accident.
According to the pre-buy inspection paperwork, under the visual inspection section, the mechanic “opened panels to inspect attached connections of cables” and checked the “free movement of flight control.”
According to the airframe maintenance logbook, the airframe had accumulated 5,025.5 hours at the time of the accident. The most recent annual inspection was completed on Sept. 19, 2022, at a tachometer time of 4,970.4 hours. The maintenance entry noted that the mechanic “lubricated all flight control cables.”
There were no other remarks about flight control cables in the maintenance entry.
Finally, the mechanic noted that the work was completed in accordance with “the C-172 service manual section 2, 12, and FAR 43 Appendix D.”
There was an affidavit from the previous owner that indicated the original maintenance logbooks were lost, and when they were located, they would be given to the new owner.
According to the manufacturer’s recommended inspection time limits, every 100 hours the “aileron structure, control rods, hinges, balance weights, bellcranks, linkage, bolts, pulleys, and pully brackets — check condition, operation, and security of attachment.”
Furthermore, it stated that the ailerons and cables were to be inspected every 200 hours to “check operation and security stops. Check cables for tension, routing, fraying, corrosion, and turnbuckle safety.”
The Cessna 172 Series Service Manual Section on Corrosion indicated under the Typical Corrosion Areas, section C – Steel Control Cable:
Checking for corrosion on a control cable is normally accomplished during the preventative maintenance check. During preventative maintenance, broken wire and wear of the control cable are also checked.
If the surface of the cable is corroded, carefully force the cable open by reverse twisting and visually inspect the interior. Corrosion on the interior strands of the cable constitutes failure and the cable must be replaced. If no internal corrosion is detected, remove loose external rust and corrosion with a clean, dry, coarse weave rag or fiber brush.
Federal Aviation Regulations Part 43 Appendix D – Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100-Hour Inspections, stated that: “…each person performing an annual or 100-hour inspection shall inspect (where applicable) the following components of the cabin and cockpit group: …(5) Flight and engine controls — for improper installation and improper operation… (7) All systems — for improper installation, poor general condition, apparent and obvious defects, and insecurity of attachment.”
Probable Cause: Maintenance personnel’s failure to detect the corroded aileron cable during recent inspections, which resulted in the separation of the aileron control cable and a subsequent loss of airplane control during takeoff.
NTSB Identification: 192246
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This May 2023 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.
