Jerry Jones Learjet Crash
Very good info here that might answer some questions.
ATL01FA021HISTORY OF FLIGHT
On January 14, 2001, at 1345 central standard time, a Learjet LJ-60, N1DC, collided with two deer during landing and ran off the end of runway 7 at the Troy Municipal Airport, Troy, Alabama. The airplane was registered to and operated by Ark-Air Flight Inc. The business flight was operated under the provisions of Title 14 CFR Part 91 and visual flight rules. Visual meteorological conditions prevailed, and an IFR flight plan was filed. The Airline Transport pilot (ATP) and ATP rated first officer received serious injuries, and the airplane was destroyedand there was a post-impact fire. The flight originated from Love Field in Dallas, Texas, at 1030 on January 14, 2001.
According to witnesses, the airplane collided with the deer shortly after touchdown and continued down the runway with the tires smoking, and veered off the right side of the runway near the end, crossed a taxiway, and impacted into a ditch and burst into flames. Local rescuers were able to extricate the crew before the fire engulfed the cockpit. According to the pilots, the thrust reversers failed to operate when engaged.
PILOT INFORMATION
The pilot held an airline transport pilot certificate with ATP privileges for airplane multiengine land, with type ratings in the Learjet LJ-60. He also held commercial pilot privileges for airplane single engine land, and was a certified flight instructor for airplane single and multiengine instrument airplanes. The pilot reported 20,750 total civilian hours on his most recent second class medical certificate, dated June 5, 2000, with no waivers or limitations. The pilot's most recent biennial flight review was in May of 2000, in the Learjet LJ-35.
The first officer held an ATP certificate with privileges for airplane multiengine land. He also held commercial pilot privileges for airplane single engine land, and was a certified flight instructor for airplane single and multiengine instrument airplanes. The first officer reported 3,500 hours total flight time in all aircraft with 750 hours in the LJ-60. The first officers most recent first class medical certificate was dated February 7, 2000, with no waivers or limitations. The first officers most recent biennial flight review was dated May of 2000, in the LJ-60.
AIRCRAFT INFORMATION
The Learjet LJ-60, S/N 60-035, N1DC, was manufactured in 1994. FAA records show the airplane was registered to Ark-Air Inc., on June 12, 1997. The maintenance records revealed the airplane was on a manufacturer's inspection program and was last inspected on August 8, 2000. The airplane had accumulated a total time of 2,088 hours at the time of the accident, including 241 hours since its last inspection.
METEOROLOGICAL INFORMATION
Visual Flight Rule conditions prevailed at the time of the accident, with visibility at 10 statute miles, ceiling at 8000 feet above ground level, temperature 16 degrees Celsius, dew point 8 degrees Celsius, wind 170 degrees at 8 knots and altimeter 30.19 inches of mercury.
WRECKAGE EXAMINATION
Heavy black skid marks were noted beginning at the first taxiway turnoff about 1500 feet down the 5,010 foot runway. Two fragmented deer carcasses were found several hundred feet after impact. The skid marks continued for about 2,500 feet and departed the right side of the runway near the Instrument Landing System shack at the end of the runway and proceeded an additional 500 feet over grass and dirt. The airplane was found resting on its left side down an embankment. The cockpit section of the fuselage was crushed upward into the crew seats. The fuselage aft of the cockpit was consumed by the post crash-fire. Examination of the landing gear found all three gear collapsed and deer fur was found lodged in the squat switch on the left main landing gear. The right and left main tires had areas of rubber that were worn completely through. The flaps were found extended, and both thrust reverser’s were found in the stowed position. Examination of the cockpit found the throttles in idle, and the thrust reverser levers in the stowed position.
MEDICAL/PATHOLOGICAL INFORMATION
Both pilots were hospitalized with serious injuries. There was no toxicology analysis conducted.
ADDITIONAL INFORMATION
With an estimated empty weight of 15,800 pounds and estimated fuel of 1,100 pounds, it was calculated that the airplane traveled 1500 feet down the runway after touchdown in 4.2 seconds before striking the deer, the performance group at Learjet using the weather reported at Troy, Alabama (variable winds and temperature at 14 degrees Celsius) the airplane landed with a ground speed of 124 knots. At 124 knots and maximum braking applied, the airplane should have come to a complete stop in about 850 feet.
A sound spectrum study was conducted using the Cockpit Voice Recorder as the source of the sound. The study was conducted by the National Transportation Safety Board's Vehicle Recorders Division. The study revealed that the engines fan speed increased from 8727.5 (82.3 percent) rpm to 9590 (90.4 percent) rpm between 11 seconds after touchdown and 18.2 seconds after touchdown. This increase in fan speed does not achieve the calculated takeoff N1, however, this engine speed is higher than achievable on a reverse thrust schedule. According to Pratt and Whitney of Canada, N1 is governed during reverse operations. The governing limit varies, and is based on ambient conditions and the airspeed. At 100 knots or greater, the maximum governing limit for N1 should be about 85.2 percent (according to Bombardier Aerospace) instead of the 90 percent found on the engines 20.4 seconds after landing.
Normal operating procedures include deploying the thrust reversers within 4 to 6 seconds after landing. Pilots deploy thrust reversers (T/R) by raising piggyback levers located in the cockpit with the throttles. With the loss of the squat switch on the left main landing gear, the T/R relay box deenergized the deploy solenoid and the T/R's go to the stow position. The electronic engine control (EEC) commands the engine speed to go to idle. As the T/R's complete the stow cycle, the unlock switches open, signaling the T/R relay box to remove the discrete signals. The EEC's switch to the forward thrust schedule and within 2.6 seconds estimated, and if the piggybacks remain at the max reverse position the engines rpm begins to increase to near takeoff power.
The airplane was released to the owners representative USAIG 2635 Century Parkway Suite 120, Atlanta, Ga. 30345.
