Incident Overview
On July 19, 2012, at approximately 2200 eastern daylight time, a Flight Design GMBH model CTLS, registration N21ZA, sustained substantial damage while landing on runway 7 at Lorain County Airport (LPR), Elyria, Ohio. The aircraft was operated under 14 Code of Federal Regulations Part 91 as a personal flight, with the private pilot as the sole occupant. Visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The local flight originated at an unconfirmed time.
Pilot Account
The pilot reported performing takeoff and landing practice. He completed three landings during daylight and was pleased with them. After a 45-minute break, he took off again to conduct night landings to regain night currency requirements. On the first night landing, he misjudged the landing and bounced. He executed a go-around and attempted another landing, again misjudging and experiencing a hard bounce. The airplane came back down, striking the nose wheel. After stopping, the pilot noticed something wrong and discovered a flat nose tire upon deplaning. He pushed the airplane from the runway and obtained a tow from ramp personnel.
Aircraft Damage
The airplane sustained damage to the landing gear, engine mount, and firewall. In this incident, the right composite main landing gear leg fractured. A subsequent incident on October 17, 2012, involving the same airplane also resulted in a fracture of the right composite landing gear leg, with minor damage.
Examination of Landing Gear
The damaged right main landing gear leg was retained for examination. The leg was constructed of composite materials, including unidirectional glass fibers, glass fiber fabric, and basalt fiber fabric. Flexible plastic tubes extended the length of the leg, enclosed within ribbed plastic tubes near the leading and trailing edges. Foam filled the space between the tubes and a center internal cavity. The legs were manufactured in a mold with a split line at the leading and trailing edges. During layup, layers were placed in one mold half, wrapped around internal components, and the mold closed with the other half. The center cavity was pressurized during curing.
Examination and sectioning revealed wrinkling of fibers, causing them to be angled relative to the surface rather than parallel. Several layers terminated at the leading and trailing edges, corresponding to longitudinal cracks found along those edges.
Manufacturer Response
The airplane manufacturer was contacted regarding the landing gear manufacturing process. The landing gear legs were produced by a subcontractor. The airplane manufacturer audited the subcontractor and found previous quality issues related to mold closing during manufacture. The subcontractor had recognized these issues and implemented steps to reduce recurrence. Additionally, the airplane manufacturer searched part requests and difficulty reports related to the main landing gear, finding 3 instances of complete collapse out of a fleet of 370 airplanes. Other reported fractures were discovered during inspection after hard landings or during taxi when significantly reduced stiffness was encountered.