FTW98LA334
FTW98LA334

On July 24, 1998, at 2215 mountain daylight time, CFSKC, a Cessna 500, registered to and operated by Skyward Aviation of Thompson, Manitoba, Canada, was destroyed when it collided with terrain during an aborted takeoff at Rawlins, Wyoming. The airline transport rated captain and commercial rated first officer sustained minor injuries. Visual meteorological conditions prevailed, and an IFR flight plan had been filed for the nonscheduled international cargo flight operating under Title 14 CFR Part 129 and Canadian Aviation Regulation 704. The flight was originating at the time of the accident.

The airplane was loaded with 800 pounds of electronic equipment (valued at $300,000) and 324.8 gallons of Jet-A fuel. Gross weight was computed to be 11,703 pounds (operating empty weight, 6,939 pounds; fuel, 3,550 pounds; crew, 364 pounds; freight, 800 pounds; baggage, 50 pounds). Takeoff was made on runway 22. Using an altimeter setting of 30.25 inches of mercury, 17 degrees C. (63 degrees F.), a calm wind, and zero flaps, the crew arrived at the following takeoff data (because the crew wanted to insure they had the required takeoff distance available before landing at Rawlins, this data was computed prior to their arrival): fan speed, 94.6%; V1, 105 knots.; Vr, 105 knots.; V2, 115 knots. The required takeoff distance was calculated to be 6,530 feet. Runway 22 is 7,008 feet long. The airport is situated at an elevation of 6,813 feet msl. This investigator computed the density altitude to be 8,187 feet msl.

The captain said that during the takeoff roll, the airplane felt "sluggish" which he attributed to the high density altitude. At V1/Vr, the airplane was rotated for liftoff. It climbed about 10 feet, "shuddered," and began to sink. The captain elected to abort the takeoff. He landed the airplane on the runway, applied brakes and deployed the drag chute at a speed estimated to be between 110 and 115 KIAS (knots indicated airspeed). In his accident report, the captain wrote: "On deployment, a momentary deceleration was experienced as the chute inflated, followed by what appeared to be the release of the chute." The airplane went off the runway at an estimated speed of 80 to 90 KIAS, down a hill, through a fence, across a road and a grassy area, across another road and through a chain link fence. The airplane then collided with a power pole and came to rest in close proximity to three parked vehicles. The airplane then caught fire. Because of their close proximity to the airplane, the three parked vehicles were also destroyed by the fire. Both crewmen exited the airplane. Postaccident examination of the runway disclosed 1,800 feet of skid marks.

In his accident report, the captain wrote: "The failure of the equipped drag chute, and the decision to abort beyond the call of V1 resulted in the aircraft leaving the departure end of the runway and coming to rest some 2,500 to 3,000 feet beyond." In addition:

1. "The crew had calculated the takeoff distance using inappropriate tables for that serial number aircraft. The correct data would have resulted in a higher fan speed, and an increase in V1, rotate speed, and V2." Asked what tables were used to calculate the takeoff performance, the captain said they used training charts provided by SimuFlite. The data contained in these tables had been previously cross-checked with data provided by Cessna in a training scenario.

2. The wind had been reported as calm. "The airport radio operator later reported occasional winds of 350 degrees at 7 knots." Taking off on runway 22, then would have resulted in a 40 degree right quartering tailwind.

3. "The drag chute failed at a point approximately 8 inches from the attach point to the aircraft."

4. "The stopping distance may have been increased by moisture on the runway caused by local shower activity that began shortly...before takeoff."

5. "The brake energy available was less than the energy required to stop the tires at that ground speed which resulted in skid marks but no flat tires."

The captain concluded that "the use of incorrect data resulted in [rotating] the aircraft 4 to 5 knots prior to actual rotate speed." In addition, "a sudden wind change [resulted in] the aircraft lifting off then approaching to, or entering a wing stall condition. The failure of the drag chute...led to the inability of the aircraft to decelerate..."

The drag chute was sent to the Canadian Aviation Safety Board's laboratory for analysis. According to their report, the riser fractured at a point where it passes through a lightning hole, and noted that "although the fractured end [showed] some of the 'frazzled' appearance normally associated with an overload failure, a significant portion of the fracture [had] a square appearance normally associated with a cut." Specimens from the remaining riser failed in tension at 4,900 pounds. Examination of the lightning hole disclosed no evidence that a nylon grommet (MS21266-2N) had been installed (as depicted in the aircraft parts manual).

The Canadian Aviation Safety Board's laboratory concluded that the riser fractured as a result of chafing at a point where it passed through the lightning hole, and that the chafing "was the result of contact with the edge of the lightning hole" that had not been covered by a nylon grommet.

Skyward Aviation furnished another drag chute riser that had been installed on CFSKC for comparison. The operator reported this drag chute was newer, and had been used less than six times. This riser also showed signs of chafing where it passed through the lightning hole.

According to the Cessna Aircraft Company, CFSKC had been modified by the replacement of the Pratt & Whitney JT15D-1 engines with -1A engines, and 3 additional feet had been added to its wingspan. These changes resulted in an increase in gross weight, pressurization differential, and engine thrust.

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