NTSB Factual Report

HISTORY OF FLIGHT

On November 25, 1997, at 0103 central standard time, a Cessna 172E, N5332T, owned and operated by a private pilot, sustained substantial damage during a night forced landing off airport, near Topeka, Kansas. The pilot received fatal injuries and both passengers sustained serious injuries. The personal 14 CFR Part 91 flight originated at Kansas City, Missouri, at 2330 (November 24), with the intended destination of Salina, Kansas. A surviving passenger stated that the airplane made an unscheduled landing at Lawrence, Kansas, due to a rough running engine. He said that after an inspection failed to reveal the nature of the problem, the airplane again departed for Salina. He said that after climbing to about 2,200 feet the airplane again experienced a rough running engine and eventually quit entirely. The pilot conducted a night forced landing, striking a wire, prior to impacting the terrain. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file.

According to a surviving passenger, the intention of the flight was to depart Salina, Kansas, proceed to Kansas City, pick up his brother, and return to Salina. He said that he and the pilot were acquaintances from their work and had planned the flight previously. He said he met the pilot at the airport in Salina and assisted him in fueling the airplane. He said that the fuel tanks were topped off with automotive fuel from a metal can through a screened funnel. He said that the flight from Salina to Kansas City was uneventful.

He said that the return flight was conducted during the hours of darkness. He said that after departure, the pilot climbed the airplane to 4,500 feet. He said that while in cruise flight the engine began to run rough. He indicated that the pilot used carburetor heat and this helped smooth out the engine. He said the pilot explained about carburetor icing. The passenger said that over a span of several minutes, the engine began to run rough again, and again the condition improved when the pilot applied carburetor heat. He said that the pilot decided to divert to Lawrence, Kansas, in order to check out the airplane. He said the landing was uneventful, and the pilot removed the air filter to have a look. He said that he found nothing; however, wiped out the interior of the inlet, and reinstalled the filter. He said that the pilot then "sumped" the fuel tanks, but found nothing unusual in the fuel. He said that they got back in the airplane with the intention of continuing the flight to Salina. He said that the engine started immediately, and the pilot checked the engine at 1,500 RPMs a "couple" times. He said that the pilot then said he would continue with the "carburetor heat on one-quarter way." He said that at that point the pilot set the carburetor heat partially in the on position.

The passenger/witness said the airplane climbed to 2,200 feet, but soon after began to run rough. He said the pilot pulled the carburetor heat out again and it "cleared out," but in a few minutes lost power again, after which, the engine responded to application of carburetor heat with "only little power, about 1,500 RPM." He said that the engine ran like this for a short time and then "the engine died."

He said that the Philip Billard Airport, near Topeka, was in sight, and the pilot headed for it, but the airplane was unable to glide that far. He said that they talked about the impending forced landing and prepared for it. He said he did not remember the actual impact.

PERSONNEL INFORMATION

The pilot, born September 26, 1952, was the holder of a private pilot certificate issued July 21, 1995. At the time of the accident he had accumulated a total flight time of about 225 hours. According to his personal logbook, all of the pilot's flight time was in the accident airplane. He had received a biennial flight review on August 2, 1997. He was the holder of a third class medical issued on October 10, 1997, with the limitation: "Corrective lenses for distant vision required."

AIRCRAFT INFORMATION

The airplane was a Cessna 172E, N5332T, with serial number 17251232. The airplane had accumulated total flight time of 3,388 hours at the time of the accident. The most recent annual inspection was conducted on April 20, 1997. The airplane had been operated 47 hours since the last inspection.

METEOROLOGICAL CONDITIONS

At the time of the accident a weather observation at the Philip Billard Municipal Airport, near Topeka, Kansas, was reporting visual meteorological conditions with a temperature of 42 degrees (F), and dew point of 38 degrees (F).

WRECKAGE AND IMPACT INFORMATION

The airplane initially impacted a wire strung between poles alongside a road running perpendicular to the direction of flight. The first indication of ground impact was on the opposite shoulder of the road where an impact gouge on the ground, in the direction of travel was located. The airplane continued down a steep downhill embankment, where the next ground marks were in the bottom of a ditch. At that point the nose landing gear was located. About 35 feet beyond that the airplane came to rest inverted. The engine was broken away from the firewall and hung by the cables. Both wings and the tail cone were damaged from ground impact. The flaps were fully retracted. Wire marks were found on the nose landing gear piston consistent with a wire strike. Continuity was established between all flight and engine controls. The throttle control was found out, as was the carburetor heat control. The mixture control was full in. A check of the carburetor venturi found it in place and intact. When the airplane was turned over fuel began running out of fractures in fuel lines. Several samples were taken and no indication of contamination was found. One blade of the propeller was bent aft. There was no apparent bending or twist in the blade. The other blade showed no evidence of bending. There was no polishing or nicks of the leading edges of either blade.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination of the pilot indicated his death was due to multiple blunt trauma injuries. The autopsy failed to reveal any physiological condition other than those injuries attributed to the accident. Toxicological examination of specimens from the pilot indicated dextromethorphan, an over-the-counter cold medication.

TESTS AND RESEARCH

The engine was removed and shipped to Continental Motors in Mobile, Alabama, for examination and test run. On February 23, 1998, the engine was prepared at the Continental Motors facility for a test run. There was impact damage to the oil sump, front engine mounts, one intake pipe, and two high-tension ignition leads. The carburetor was broken off. The carburetor was replaced with a serviceable unit. The intake pipe at number two cylinder was replaced with a serviceable pipe. The oil sump and ignition leads were repaired with epoxy.

The engine was mounted on a test stand and placed in a test cell. The engine was primed and startup was immediate. The engine was idled at 650 RPM and oil pressure came up to over 40 PSI. When the oil temperature reached 100 degrees (F), it was run up to 2,540 RPM. Acceleration checks were performed from about 650 RPM to 2,500 RPM several times. The engine responded to acceleration without hesitation.

After the engine run, the engine was re-crated and shipped to a destination specified by the pilot's wife who was in possession of the airplane wreckage at that point.

ADDITIONAL INFORMATION

The Federal Aviation Administration, Advisory Circular AC 20-113 dated October 22, 1981, states under the title under the title "In-flight Winter Weather Conditions," and the sub title, "Prevention Procedures," "The pilot should remember that induction system icing is possible, particularly with float type carburetors, with temperatures as high as 100 degrees (F) and the humidity as low as 50 percent. It is more likely; however, with temperatures below 70 degrees (F) and the relative humidity above 80 percent. The likelihood of icing increases as the temperature decreases (down to 32 degrees F) and as the relative humidity increases. The circular continues, "... When no carburetor air or mixture temperature instrumentation is available, the general practice with smaller engines should be to use full heat whenever carburetor heat is applied."

A copy of "Icing Probability Curves," from a Federal Aviation Advisory Circular is attached to this report as an addendum.

Parties to the investigation were the Federal Aviation Administration, Flight Standards District Office, Wichita, Kansas; Cessna Aircraft Company, Wichita, Kansas; and Continental Motors, Mobile, Alabama.

The wreckage was released to the pilot's wife on December 2, 1997.

NTSB Probable Cause

the pilot's improper use of carburetor heat. Contributing factors were carburetor icing conditions, dark night conditions, and the transmission wire.