Introduction
On 18 September 2015 at 1830 UTC, a Vans RV-9A aircraft, registration G-XSAM, experienced a nose landing gear collapse during the landing roll at Old Sarum Airfield in Wiltshire. The aircraft, manufactured in 2008 and powered by a single Wilksch WAM-120 piston engine, was conducting a private flight with one pilot and one passenger aboard. Neither occupant was injured, but the propeller, nose, and nose landing gear sustained damage.
History of the Flight
The pilot, a 35-year-old Commercial Pilot Licence holder with 3,046 total flying hours (including only 2 hours on this type), was landing on grass Runway 24. He reported that the touchdown and initial part of the ground roll were normal. As the aircraft slowed, the nose landing gear collapsed backward, causing the nose and propeller to strike the ground before the aircraft came to a halt.
Pilot's Account
The pilot stated he was unsure why the collapse occurred. He believed his landing technique was no different from three previous landings he had performed earlier that day and two he had observed conducted by the aircraft owner. He said he applied suitable back pressure on the control column during the landing roll. Although the runway was bumpy, he did not recall any major bumps.
Examination and Damage
Examination of the aircraft revealed that the nose landing gear leg had folded backward, and the nosewheel fork was distorted relative to the leg. The damage pattern was consistent with overload forces. According to previous experience with this type of nose gear, such damage typically occurs when the nose landing gear is subjected to high loads that cause the nosewheel fork to bend and dig into the ground. The resulting drag on grass runways then usually causes the leg itself to collapse backward in bending near its mounts.
Relevant Guidance
The Light Aircraft Association (LAA) Type Acceptance Data Sheet for the Vans RV-9 and RV-9A includes a paragraph describing problems with the RV-9A nose leg, particularly when operating on grass. It emphasizes the importance of maintaining correct nosewheel tyre pressure, ensuring generous clearance between the tyre and the wheel spat (about half an inch), maintaining suitable preload on the nosewheel axle bearings, and landing on the mainwheels first while holding the nosewheel off the ground during the initial landing roll to avoid wheelbarrowing and overloading the nosewheel. Additionally, a Vans Service Letter dated 9 November 2007 advised keeping the stick fully back when taxiing, especially after touchdown.
Note on Lighting Conditions
The landing occurred approximately 15 minutes after official sunset. It is not known whether this factor had any bearing on the accident.