Saturday, July 11, 2020

Sopwith 1½ Strutter, N5539: Accident occurred July 03, 2020 in Van Alstyne, Texas

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. 

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Dallas, Texas

Location: Van Alstyne, TX
Accident Number: CEN20LA259
Date & Time: 07/03/2020, 1000 CDT
Registration: N5539
Aircraft: LANKENAU Sopwith 9400
Injuries: 1 Minor, 1 None
Flight Conducted Under: Part 91: General Aviation - Flight Test 

On July 3, 2020, a Sopwith 9400 experimental airplane, N5539, was destroyed when it was involved in an accident near Van Alstyne, Texas. The pilot received minor injuries and the passenger was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight.

According to the pilot this was the 23rd test flight of the airplane, which was built following original design drawings. The flight was scheduled to be a short flight to confirm flying and landing wire deflections, flight control synchronization while under air loading, and to perform an aerial reconnoiter for potential obstacles at the approach end of the runway. A second crewmember was also on-board, responsible for monitoring cable deflections and vibrations, control surface positions during flight (ie; drooping aileron, elevator or etc.), and communicating with the ground crew via cell phone text.

The airplane performed normally through the first overflight of the airfield and a series of turns. As the pilot conducted a left turn he moved the control stick to the right to bring the wings level. There was no noticeable resistance and the control stick continued until it had reached its maximum travel. The pilot recognized this as a failure in the lower aileron circuit. Not knowing the exact location or cause of the failure, the pilot maintained the control stick at it's far right extent and waited for the effects of the dihedral to slowly bring the wings back to level, all the while maintaining marginal control with back pressure on the elevator and right rudder to keep the nose from falling off. The airplane eventually settled wings level with a slight nose down attitude on a northeasterly heading about 350' AGL and 75 IAS.

The pilot elected to perform an emergency landing in the cornfield in front of the airplane. The pilot cut power to the engine during approach, and after cutting the engine power he was unable to clear trees during the emergency descent. The airplane brushed a tree and descended into the ground nose down and in a turn.

The pilot examined the wreckage and determined the cause of the failure. There is a rocking tube that connects the front of the front cockpit to the rear control stick. The aileron cables connect to a horn which is affixed to this tube. The tube had worked its' way rearward about 1", which was sufficient for the front part of the tube to come loose from its' socket. The pilot found a flaw in the design of the original dual control configuration that allowed the tube to move rearward and cause the separation.

Aircraft and Owner/Operator Information

Aircraft Make: LANKENAU
Registration: N5539
Model/Series: Sopwith 9400
Aircraft Category: Airplane
Amateur Built: Yes
Operator: On file
Operating Certificate(s) Held:None  

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation:
Observation Time:
Distance from Accident Site:
Temperature/Dew Point:
Lowest Cloud Condition:
Wind Speed/Gusts, Direction:
Lowest Ceiling:
Altimeter Setting:
Type of Flight Plan Filed:
Departure Point:

Wreckage and Impact Information

Crew Injuries: 1 Minor
Aircraft Damage: Substantial
Passenger Injuries: 1 None
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Minor, 1 None
Latitude, Longitude:

VAN ALSTYNE, Texas (KTEN) -- A World War I military aircraft replica with two people onboard crashed in a corn field near Van Alstyne Friday morning, and its pilot was being treated for injuries.

The call for help went out about 9:45 a.m. at the crash site along Milam Road.

"I heard the plane come over my shop," said Jamie Marion. "It was just spitting and sputtering, and it looked like it was already starting to go down."

The single-engine plane appeared to clip a tree before going down.

"Luckily, a Frisco off-duty police officer lives around here," said Van Alstyne police Officer Jeremy Bigler. "He took me on the Gator. We went into the middle of the corn field. We were able to see plane tip in the cornfield and we located the plane."

First responders searched the field for about an hour before finding the pilot, later identified by the FAA as Kip Lankenau. He was airlifted to a hospital for treatment of a compound ankle fracture. Passenger Bruce Kimme was not seriously hurt; he told us off-camera he just suffered a few bruises.

In a Facebook post last month, Lankenau identified the biplane as a replica of a Sopwith 1½ Strutter, which was originally developed in Britain and was first placed in service 114 years ago.

Lankenau's company, Kip Aero, sells kits of this aircraft to aviation enthusiasts. Its fuselage is made of wood; the wings are covered in fabric.

The reproduction is classified by the FAA as "experimental." It received its airworthiness certificate about one year ago.

According to Wikipedia, very few examples of the original Sopwith 1½ Strutter have survived.

A World War I-era replica airplane crashed in a corn field near Milam Road outside of Van Alstyne on July 3.

Witnesses say the plane appeared to clip a tree before going down.

There were two people on board the aircraft. The pilot, later identified as Kip Lankenau, was transported by helicopter to a local hospital with a broken leg. He is expected to make a full recovery.

The other person in the plane was Bruce Kimme. He reportedly only sustained minor injuries.

The crash occurred in a remote corn field that was inaccessible by car.

Van Alstyne Police Officer Jeremy Bigler was one of the initial first responders on the scene. He told a local television station that an off-duty Frisco firefighter who lived nearby used his off-road vehicle to help reach the scene of the crash.

It reportedly took first responders nearly an hour before they were able to locate Lankenau.

The plane Lankenau was flying was a replica of a Sopwith 1½ Strutter. The original plane was developed by British Engineers nearly 115 years ago. Lankenau’s company, Kip Aero in Dallas, manufactures replicas, which the FFA has classified as “experimental.”

According to the company’s website, buyers can purchase replica aircraft as a complete kit or a series of sub-kits.


  1. Hope they recover and are able to continue. Let's hope whatever caused the reproduction Gnome Monosoupape 100hp engine to sputter can be figured out and resolved. Nice to see a classic engine revived.

    1. It was not engine failure; it was a flaw in the original palns specific to the dual controls of the Sopwith 1 1/2 Strutter. PIlot turned OFF the engine prior to making the emergency landing.

  2. Preliminary report says the aileron control was lost after a control tube worked loose. Design problem, was testing the plane. No engine failure.


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