Douglas DC-6A accident at Idlewild Airport, N.Y., 21 Jun 1957 (N-34953)

Accident narrative

On June 21, 1957, at 1051, a Douglas DC-6A leased and operated by Flying Tiger Line made a forced landing on a sandbar in Jamaica Bay, two miles southwest of its takeoff from New York International Airport (Idlewild). The aircraft, N 34953, suffered a loss of power on all four engines. The five flight crew members were uninjured, and two of the four company employee-passengers sustained minor injuries. The aircraft received substantial damage from the wheels-up landing and salt water immersion.

### The flight

The flight was a ferry trip to Dover, Delaware, where it was scheduled to transport military freight to Chateauroux, France. The crew consisted of Captain Gregory P. Thomas, who had 13,000 pilot hours with 300 in the DC-6; Copilot William H. Seamans, with 14,000 hours and 80 in the DC-6; Flight Engineer B. J. Palamar; and Stewardesses Russon and Johnson.

The aircraft’s gross weight was 74,977 pounds, well below the allowable takeoff weight of 100,000 pounds. The 1051 weather at Idlewild was high, thin scattered clouds with visibility over 15 miles.

### The emergency

The takeoff from runway 31R began at approximately 1048. Crew statements indicated that a normal engine runup had been made at 30 inches of manifold pressure, with all pressures and temperatures normal. In accordance with the company operations manual, a wet takeoff was made using 2,800 r.p.m., 59.5 inches of manifold pressure, and 240 brake mean effective pressure (BMEP).

After breaking ground and reaching an altitude of about 140 feet over the end of the runway, the BMEP of the No. 3 engine dropped to 105. This was immediately followed by a similar drop on the other three engines. The crew reduced manifold pressure to 50 inches, which did not correct the difficulty, and then returned it to 59.5 inches.

Idlewild local control was advised of the emergency and cleared the flight to land on any runway. The aircraft passed near the approach end of runway 13R, but its altitude was too low to permit a further left turn to the runway. The captain testified that he had to go straight ahead with the small amount of power remaining, as he was unable to maintain altitude at an airspeed of 105 knots. The aircraft made a descending left turn and landed wheels-up on a sandbar, with flaps fully extended, coming to rest on the fuselage bottom.

### What the investigation found

Because the power loss occurred nearly simultaneously on all four engines, investigators immediately sampled the aircraft's fuel and antidetonant injection (ADI) fluid. The gasoline was found to be the correct octane and uncontaminated. However, laboratory analysis of the ADI tanks revealed a mixture of 55 percent correct ADI fluid (50/50 methanol-water) and 45 percent ethylene glycol, a fluid used to eliminate ice on aircraft exterior surfaces.

The investigation traced the contamination to the morning of the flight, when a mechanic filled the aircraft's ADI tanks from a portable cart marked "ADI." Samples from this cart showed it contained entirely ethylene glycol.

The cart had been replenished two days earlier from a fenced outdoor drum-storage area outside the Flying Tiger hangar. Investigators found that drums containing ADI fluid, ethylene glycol, and other liquids were intermingled in this area. All drums were marked on one end, but mechanics filled the portable cart by inserting a hand pump into a side bung where there were no markings.

In a deposition, the uncertificated mechanic who serviced the cart stated that he had mistakenly filled it from an ethylene glycol drum. He noted he had previously serviced the ADI cart but had never drawn fluids from the outdoor supply before. Investigators observed that the stenciling on the drum he used, while dirty and blurred, was distinguishable as ethylene glycol.

Examination of the engines at the sandbar showed no structural failures. The Board tested the No. 1 engine on a stand using dry power and correct ADI fluid, and it operated normally. When the contaminated mixture found on the flight was introduced at wet takeoff power, the exhaust flame changed from whitish-blue to deep orange within 40 seconds. Torque pressure dropped by nearly half, equivalent to a horsepower drop from approximately 2,350 to 1,225. Cylinder head temperatures rapidly exceeded maximum limits, and the ignition analyzer indicated progressive spark plug fouling in all cylinders.

The Board noted that the crew could not have detected the contamination during the pretakeoff check, as normal runup procedures at 30 inches of manifold pressure do not trigger the flow of ADI fluid. The Board commended the pilots for ably handling the serious situation and avoiding populated areas.

The investigation revealed that usual air carrier standards for storing and marking fluids were not in effect at the hangar. The Board found a serious lack of managerial supervision, a lack of orderly separation of the drums, and a definite lack of instruction for mechanics servicing the ADI cart.

### Probable cause

The Board determines that the probable cause of this accident was "the loss of power on all engines immediately after a wet takeoff due to (A) contamination of ADI fluid resulting from (B) mechanic's mistake in replenishing ADI supply cart with ethylene glycol (de-icing fluid), and (C) inadequate supervision of storage facilities."