CEN13IA285

The failure of the airplane’s parachute to deploy when activated during a loss of control in cruise flight due to the dynamic maneuvering of the airplane at the time of the activation, which exceeded the parachute system’s certification requirements.

The pilot reported that he lost airplane control during cruise flight in instrument meteorological conditions (IMC) and turbulence. He subsequently activated the airplane's parachute system, but the parachute failed to deploy. The pilot regained control of the airplane after exiting IMC and landed the airplane without further incident. Certification tests were performed from level flight at speeds ranging from 62 to 137 knots indicated airspeed, and one test included deployment of the parachute system after a one-turn spin. The testing showed that to minimize the chances of parachute entanglement and reduce aircraft oscillations under the parachute, the parachute system should be activated from a wings-level, upright attitude if possible. Postincident examination of the parachute system did not reveal any system component failure. Postincident testing showed that off-axis deployment of the parachute could exceed the forces required for a successful deployment of the parachute. If the airplane has a large pitch or bank angle or angular rates (or a combination of these) as the parachute rocket leaves the airplane, the airplane will rotate and cause the rocket tether to pull at an angle other than that intended, and the parachute will fail to deploy. Radar data showed that the airplane was in a very dynamic flight pattern with extreme pitch and bank angles when the parachute system was activated. Thus, the parachute likely failed to deploy when activated due to the dynamic maneuvering of the airplane at the time of the activation, which exceeded the parachute system's certification requirements.

The incident airplane was not equipped with a remote data module. Materials Examination of CAPS Components CAPS components from the incident airplane were submitted to the NTSB Materials Laboratory for examination. The examination revealed a hole present on the on the retaining harness cover located where the cover rested at the upper aft corner of the parachute enclosure compartment. The exterior surface in the area around the hole appeared to have a light to dark gray tint. The fabric in the vicinity of the hole was wrinkled and felt relatively stiff. The red retaining strap adjacent to the hole was displaced, wrinkled, and stiff. The edges of the hole were relatively rough, and some of the edges were folded over. Individual fibers were visible at the hole edges when viewed under optical magnification. Broken fibers near the area of the hole tended to accumulate at the weave intersections. The accumulated fibers were rounded and globular consistent with heating. The accumulated fibers at the weave intersections were darkened and fused together. The accumulated fibers were rounded and globular consistent with heating. The grommets in the retaining straps exhibited impressions on the forward faces of the grommets corresponding to contact with the release pins. The fabric around the grommets appeared stretched around the grommets and fibers were pulled out at the upper side of the grommets. A series of sliding contact marks were observed on the release pin at the right side of the D-bag assembly. The marks had parallel scratches and lipped edges consistent with heavy sliding contact with a relatively hard object and were not consistent with vibration wear. The locations of the marks were near the base of the pin. The location and shape of the marks were not consistent with contact with the grommet on the retaining straps. Aside from the grommets, the only other metal item in the vicinity of the release pins was the quick connector link between the incremental bridle and the D-bag lanyards. However, no corresponding contact marks were observed on the quick connector link. Also, the quick connector link had a zinc coating. The contact marks on the release pin were analyzed using energy dispersive x-ray spectroscopy (EDS) in a scanning electron microscope. The EDS spectrum showed peaks that were consistent with the stainless steel. No evidence of zinc was observed on the release pin. Plots of Radar Data and Performance Estimates Plots of radar data and performance estimates for the flight were prepared by a National Transportation Safety Board (NTSB) National Resource Specialist, Aircraft Performance. These plots used secondary radar returns and relevant primary radar returns in the area of the incident, curve fits through that data to estimate airplane position, performance parameters computed from curve fits, and 'math pilot' and 'manual' attempts to match the curve fit trajectories with simulations. Figure 2 – Plan and 3D Views of Radar Data and Simulation Flight Tracks (Note: The 3D view uses an exaggerated vertical scale) Modeling of the airplane's flight path through the radar data revealed that the flight was very dynamic with extreme pitch and bank angles (knife edge flight, bank angles greater than 90°, etc.). It appeared that the pilot's radio call about having deployed the parachute comes near the apex of a very steep climb, at which almost all the airplane's energy is sacrificed to make the climb (this was one of the places in the manual (simulation) flights where the airplane ran out of energy and could not match the target climb). Because of all the twists and turns that precede this point, it seems possible that the parachute rocket may not be pulling the parachute from the airplane at the intended angle after it is deployed. If the airplane has a large pitch or bank angle or angular rates (or combination of these), as the parachute rocket leaves the airplane, the airplane will rotate and cause the rocket tether to pull at an angle other than that intended. Off-Axis D-Bag Pull Tests After the incident airplane was ferried to CDC, Duluth, Minnesota, the NTSB IIC requested that off-axis pull tests of the D-bag be performed. The incident D-bag was used for testing, which was carried out at various trajectories using a gantry, a cable attachment to the bag, a load cell, and a hand-crank. The vertical trajectories were 5 to 55 degrees relative to the horizontal in 10 degree increments and later trajectories from the aft direction, 45 degrees from aft, and 90 degree from aft. The results of pull force and D-bag distance movement were recorded. Testing was stopped when the D-bag reached a point where it would begin to pivot on the compartment edge or to prevent damage to the bag/airplane. The NTSB IIC requested that CDC graphically plot the recorded results relative to the airplane diagram. A quarter spherical plot centered over the CAPS compartment was defined with three zones. The green zone depicted a trajectory with an extraction force of 150 lbs or less. The yellow zone depicted a trajectory with an extraction force exceeding 150 lbs. The red zone depicted an extraction force exceeding 200 lbs. Figure 3 - 3D Representation of Extraction Results D-Bag Dimensional Measurements Using a tape measure, perimeter lengths of the incident D-bag were taken between the five straps (four band areas) that wrapped the bag. Band one was referenced as the nearest band from the D-bag bottom. Band numbering was increasingly incremented toward the top of the deployment bag. The perimeter lengths were as follows: Band 1: 36 3/8 inches Band 2: 36 5/8 inches Band 3: 36 1/2 inches Band 4: 36 3/8 inches Comparison measurements of the perimeter lengths were made with four packed D-bags located at CDC, two of which were repacked and two that were returned for repack. Measurements were taken at the number three band. The perimeter lengths were as follows: BRS repack: S/N - 00866RI, pack date - December 2013, 35 3/8 inches Cirrus repack: S/N - 00908RI, pack date - June 2013, 35 7/16 inches Return for repack: S/N – 935, manufacturing date - May 2003, 35 7/8 inches Return for repack: S/N – 943, manufacturing date – May 2003, 36 1/16 inches Rocket Motor Information Four rocket motors of the same lot (110819) as that of the rocket motor that was installed on the airplane were test fired at an ambient temperature of 72 degrees F. Statistical analysis, in part, showed the following: Figure 4 - Statistical Values of Thrust and Impulse Plots of rocket thrust at three ambient temperature curves at 240 degrees F, 67 degrees F, and -27.5 degrees F, showed peak thrusts of about 240 lbs, 220 lbs, and 190 lbs, respectively. Avionics/Instrument Examination An external source of power was connected to the airplane. The AI up righted itself and displayed an approximate 0 degree pitch and bank angle indications with no anomalies and no displays of the unit's power warning flag. The AP was operated through clockwise and counterclockwise heading and in upward and downward pitch selections. All of the selections resulted in positive correlated changes in control surface movements. Wires leading to the flux gate were shaken by hand pressure and no error messages appeared. The AI was then removed for bench testing. The AI had an unbroken original seal in place on the AI case. The AI was placed on a test bench and powered with 28.0 Vdc for functional testing in accordance with L-3 Avionics Systems Component Maintenance Manual AIM Model 1100. The test results were within test specifications. Precipitation Static (P-Static) The pilot stated that during the incident, the radios were not working and he made radio calls to a Southwest Airlines flight since he did not receive a response to his calls from air traffic control. He s