NYC94FA123

The pilot (PIC) said that during takeoff, the airplane 'pulled' left before reaching V1 (takeoff decision speed) & he had difficulty maintaining directional control. He initiated an abort, but could not stop on the remaining runway. The plane crossed a concrete slab that previously supported an approach light & the main gear collapsed. The plane stopped 446' from the departure end of the runway. The outer left tire had blown during the takeoff roll, followed by the left inner tire & both right main tires. PIC was unable to obtain reverse thrust. The thrust reversers should have been (but were not) armed before takeoff; this was not included on the checklist that was provided to the flightcrew. Also, the PIC did not deploy the drag chute. Company maintenance personnel indicated the tires had been under-inflated when they were built up & installed, several days before the accident & that the tires had not been checked or reinflated after buildup. Goodyear reported the tires could have been up to 50% under-inflated. An exam of the tires disclosed evidence of under-inflation, & subsequent overheating.

History of flight

On Wednesday, July 13, 1994, at 1505 eastern daylight time, a Gates Learjet 35, N69PS, operated by Mid-Atlantic Jet Charter, Inc., sustained substantial damage during an aborted takeoff at the Atlantic City International Airport, Atlantic City, New Jersey. There were no injuries to the crew of two or the eight passengers. Visual meteorological conditions prevailed, and an IFR flight plan was filed. The flight was being conducted under 14 CFR Part 135.

The airplane was destined for Newark, New Jersey. The crew taxied to and was cleared for takeoff on runway 13, which was 10,000 feet long and 180 feet wide. The captain stated:

I don't recall the airspeed but it was before V1 the plane pulled hard to the left and I had a tough time keeping it straight...I recall seeing material flying past my window. I called for an abort, power levers to idle, max braking. I tried applying thrust reverse but it didn't work. I asked [the first officer] if he had armed the TR's [Thrust Reversers]...I looked to see [and they were armed] but they didn't work. I asked [the first officer] to apply emergency brakes and pull the parking brake....As we went off the end of the runway I felt the main gear sheer and we were sliding on the nose wheel and the fuselage.

The first officer stated:

Prior to V1, [the captain] called an abort due to an abnormal directional control. I released the spoilers, armed the thrust reversers as per procedure. [T==he captain] was heavy on the brakes to no avail. I tried the emergency brakes and we continued...past the runway into the grass. We rolled over a concrete pad which relieved [the airplane] of its landing gear....I opened the passenger door and all eight passengers and crew walked out on their own power.

A witness, an airport employee, stated:

By the time the aircraft left runway 13 it appeared to be travelling [about] 40 knots....the aircraft [travelled] about 200 yards where the main gear collapsed.

The weather at the time of the accident was reported as: 4,500 scattered, 15,000 broken, 6 miles visibility, with haze, temperature 89 F, wind 180 degrees at 12 knots.

The accident occurred during the hours of daylight, at latitude 39 degrees, 27 minutes North, longitude 74 degrees, 35 minutes West.

Personnel information

The captain, John Szuba, held an Airline Transport Certificate, with single and multi-engine land and instrument ratings. He reported a total of 5869 hours with 35 hours in this make and model airplane, of which 7 hours were in the last 30 days.

His most recent FAR Part 135 Airman Competency/Proficiency Check was accomplished on March 17, 1994, in the Learjet 25.

He was issued a First Class Airman Medical Certificate on March 4, 1994 with no limitations or waivers.

In addition to the Learjet 35, Mr. Szuba also flew the following airplanes for Mid-Atlantic Jet Charter, Inc.:

Learjet 25 Hawker Siddeley 125 Beech 100 Piper PA-31-325.

The first officer, Michael A. Sheenan, held an Airline Transport Certificate, with single and multi-engine and instrument ratings. He reported a total of 3722 hours with 50 hours in this make and model airplane, of which 7 hours were in the last 30 days.

His most recent FAR Part 135 Airman Competency/Proficiency Check was accomplished on September 8, 1993, in the Learjet 25.

His was issued a Second Class Airman Medical Certificate on September 28, 1993 with no limitations or waivers.

Aircraft information

The two left main tires of N69PS were changed on July 3, 1994 by Mid-Atlantic Charter, Inc. maintenance personnel. The airplane made four takeoffs and landings after that date. During an interview, the Director of Maintenance for Mid-Atlantic Jet Charter, Inc., stated that the tires had most likely been "built- up" on the day they were installed. In addition, he said that the tires were inflated to "115 PSI."

When interviewed at a later date, he provided the same answers. He was asked to check the Learjet 35 Maintenance Manual to verify the tire pressure PSI. When he referred to the manual, it stated the tires should be inflated to 145 psi, +/-minus 5 PSI.

N69PS was equipped with a drag chute. The Learjet model 25 operated by Mid-Atlantic Jet Charter, Inc. was not equipped with a drag chute.

Aerodrome and ground facilities

The airplane departed the runway paved over-run and impacted a concrete structure which had previously supported a runway approach light. This structure was level with the ground. By the time the airplane impacted this structure, all four tires were blown, and it was rolling on rims or parts of rims. Ditches were dug by the rims approximately 4 inches deep prior to impacting the structure.

Wreckage

The wreckage was examined at the accident site on July 13, 1994, by inspectors from the Federal Aviation Administration. A Safety Board Investigator examined the wreckage on July 19, 1994, after it had been moved to a ramp on the airport.

The main landing gears were sheared from the fuselage. The left wing was buckled. The wing flaps were torn and wrinkled. The fuselage was buckled and torn aft of the wheel well.

All four main tires were blown. Fragments of these tires were removed from the runway by airport personnel without documenting the location.

Tests and research

Tires

The remains of the tires were examined at the Goodyear Technical Center, Akron, Ohio, on August 31, 1994, under the control of Ken Shauman, an Airwothiness Inspector for the Federal Aviation Administration.

In a report, the Goodyear Chief Engineer, Aircraft Tire Engineering, stated:

The pieces from all tires showed substantial heat in the shoulder/upper sidewall area. As the temperature elevates, the strength of the nylon cord will decrease. The temperature levels that were obtained...were sufficient to cause the nylon cord to fail.

Ken Shauman of the Cleveland FSDO was present during the investigation. Upon returning to Cleveland, he called me and read the following out of the Learjet Operations Manual:

a. Proper unloaded inflation pressure for a Learjet 35...should be 145 psi, +/- 5 psi.

b. After the tire is inflated, the tire must be allowed to stand for a minimum of 12 hours and then re-inflated....

Daily inflation pressure checks are the single most important maintenance item.

Taking into consideration that these tires were under inflated initially, were installed on the aircraft immediately with no allowance for tire growth and had no inflation checks in the last 3 days, the tires could potentially have been under inflated by up to approximately 50% at the time of this takeoff.

Conclusion:

1. The tires failed due to extreme heat.

2. The extreme heat generation was due to over deflection.

3. The over deflection was due to under inflation.

Thrust reversers

The thrust reversers (T/R) were actuated using accumulator pressure and deployed three times by investigators. The thrust reversers deployed fully each time.

Airspeed indicators

The airspeed indicators were calibrated and both indicators checked wit