Aviation Accident Summaries

Aviation Accident Summary DFW08FA234

Douglas, KS, USA

Aircraft #1

N162XP

CESSNA AIRCRAFT CO E162

Analysis

The purpose of the engineering test flight was to obtain an assessment of the special light sport airplane's spin characteristics. Sixteen spins, with the aircraft in four different configurations, were planned. The aircraft successfully completed the first configuration with a set of four spins. The pilot then completed three of the four spins in the second set of spin testing. With the aircraft at 10,000 feet, the pilot initiated a spin to the left. Once the spin was established, the pilot made the planned control inputs. Despite several attempts by the test pilot to recover the aircraft from the maneuver, the aircraft continued to spin. At the planned altitude of 6,000 feet, the pilot elected to deploy the aircraft's recovery parachute and pulled the chute's activation handle. The parachute did not deploy, and the aircraft continued to spin. The pilot then elected to jettison the cabin door, exit the airplane, and deploy his parachute. The airplane descended into terrain and was substantially damaged. During a subsequent review of flight test data, the airplane manufacturer discovered that an unrecoverable spin could develop in the prototype airplane. An examination of the aircraft's parachute system revealed that the rocket system used to deploy the chute had activated, however; the parachute failed to be pulled from its canister. The parachute's incremental cord was found, and inspected; the entire series of "bar tabs" were torn; an indication that the rocket motor pulled with its full force. The signatures observed on the parachute system and aircraft components were consistent with parachute system cable contacting the right flap cable/turn buckle cable during the rocket launch sequence, compromising the parachute's deployment.

Factual Information

On September 18, 2008, approximately 1145 central daylight time, a single-engine Cessna 162, Skycatcher experimental airplane, N162XP, was destroyed when it impacted terrain during an uncontrolled descent after the pilot parachuted from the airplane near Augusta, Kansas. The airplane was registered to and was operated by Cessna Aircraft Company. The commercial pilot, the sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 Code of Federal Regulations Part 91 test flight. The flight originated at approximately 1100, to obtain an assessment of the aircraft's spin characteristics. Sixteen spins; with the aircraft in four different configurations were planned. The aircraft had successfully completed the first configuration with a set of four spins. The pilot then completed three of the four spins in the second set of spin testing. With the aircraft at 10,000 feet, the pilot initiated a spin to the left. Once the spin was established, the pilot made the planned control inputs. The airplane failed to recover from the spin. Despite several attempts by the test pilot to recover the aircraft from the maneuver, the aircraft continued with to spin. At the planned altitude of 6,000 feet the pilot elected to deploy the aircraft's recovery parachute and pulled the chute's activation handle. The aircraft's parachute did not deploy, and the aircraft continued to spin. The pilot then elected to, jettison the cabin door, exit the airplane, and deploy his parachute. The airplane impacted the ground in a wooded area. The airplane wreckage was retrieved and secured for further evaluation. There were no reported ground injuries. An examination of the aircraft was conducted on September 24, 2008, at the Cessna Aircraft Company facility in Wichita, Kansas, under the supervision of the NTSB and FAA. Technical representatives from the engine, parachute, and aircraft manufacturers were present. The airplane was destroyed upon impact with the ground. Control continuity was established to the respective flight controls. An initial examination of the aircraft's parachute system revealed that the rocket system used to deploy the chute had activated, however; the parachute failed to be pulled from its canister. In order to measure the force required to pull the parachute from its canister, the packed parachute assembly was tested at BRS, Inc. facilities. The parachute required approximately 50-lbs (of pull force) to extract the parachute from its container. The manufacturer reported a 50-lb pull, could be considered to be near the upper limit for this particular system. The BRS parachute is equipped with an incremental cord that is used to pull the parachute out of the container. On one end of the incremental cord are four Kevlar straps which are sewn on the parachute bag; the other end of the incremental cord is attached to a steel cable that is looped around a steel collar assembly. The steel collar is then placed over the rocket. The incremental cord has a series of "Bar tabs" (stitching that tears apart at a predetermined load) that attenuates the shock load on the parachute. The parachute would normally be pulled from the canister, before the entire series of "Bar tabs" are separated. The accident parachute's incremental cord was found "undamaged", but the entire series of "Bar tabs" were torn; an indication that the rocket motor pulled with its full force. The steel cable end had separated during the rocket activation; the cable displayed signs consistent with ductile overload and shear type separation. A section of the failed cable was tested in the Cessna Laboratory; and it was determined that the cable met specifications. The four Kevlar straps were numbered and indexed to their position relative to the canister. Three of the four straps appeared typical; the fourth strap (labeled #3) displayed two signatures: tightening of the weave, resulting in a "deformation set" in the strap. The second signature was that some of the stitching securing the #3 strap to the horizontal parachute bag strap had separated. The marks are consistent with a large tension load applied to the #3 strap. During parachute installation the #3 strap was positioned towards the left-rear quarter of the airplane. The steel cable had a Nicopress sleeve and thimble eye attachment. The sleeve and thimble assembly displayed two areas of impact damage. The soft copper sleeve displayed signature consistent with cable contact; a steel thimble eye displayed an area of impact damage and was bent to one side, distorting the eye. An inspection of the airplane's right flap cable swage, revealed two contact areas that consisted of a "light" gouge, and scratch marks. Signatures observed on the BRS system and aircraft components were consistent with an incremental cable contacting the right flap cable/turn buckle cable during the rocket launch sequence, compromising the parachute's deployment. A video of the incident was recorded by a chase airplane; a review of the video indicates that the angle between the rocket trajectory and the parachute canister may have been too severe to allow for proper extraction of the parachute assembly. During flight testing and the subsequent review of test data, it was discovered that an unrecoverable spin could develop. The accident airplane was a preliminary configuration and the manufacturer abandoned the configuration for production airplanes.

Probable Cause and Findings

The airplane's inability to recover from an intentional spin, despite proper control inputs by the flight test pilot. Contributing to the accident was the failure of the airplane's ballistic parachute system to properly deploy.

 

Source: NTSB Aviation Accident Database

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