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ASN Wikibase Occurrence # 133253
Last updated: 22 May 2019
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Date:20-JUN-1994
Time:18:30
Type:Silhouette image of generic H269 model; specific model in this crash may look slightly different
Hughes 269C
Owner/operator:U. S. Dept. Of Agriculture
Registration: N7404F
C/n / msn: 650414
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:London, TX -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Unknown
Departure airport:JCT
Destination airport:
Investigating agency: NTSB
Narrative:
On June 20, 1994, approximately 1830 central daylight time, a Hughes 269C, N7404F, was destroyed when it collided with trees and the ground near London, Texas. The helicopter, leased to and operated by the U. S. Department of Agriculture and flown by a commercial pilot, was on a local animal damage control flight. Company flight following was being utilized and visual meteorological conditions prevailed. The pilot and the one observer/gunner received minor injuries.

According to the operator, the flight was part of a coyote eradication program. The flight had departed the Junction, Texas, Kimble County Airport at 1730, and flown to a local ranch, where the pilot and observer met with the ground search team. Shortly thereafter, the flight departed to the search area. The pilot stated that, due to the nature of the mission and the terrain cover, he was flying the search pattern at a height of 35 to 40 feet at about 30 knots.

After searching the area for several minutes, the observed informed the pilot that he had spotted a target. Shortly after the gunner had spotted and opened fire on a coyote, the pilot felt what he described as a "short but violent" vibration in the anti- torque pedals. He said he initiated a right turn and began looking for a place to land. He then noticed that the engine RPM was dropping rapidly, the engine/rotor RPM needles were split, and the rotor RPM was bleeding off with the engine RPM. The pilot said he immediately applied full throttle, but the engine would only produce 2,000 RPM. At that point, he attempted to maneuver around some 10 foot high trees to a clear area. During the maneuver, the main rotor blades struck the trees and the aircraft rolled onto its right side and impacted the ground.

Following recovery of the wreckage, the engine was run in the accident airframe with the main rotor and tail rotor drives disconnected. The engine started on the second attempt and was run at idle power and 2,000 RPM for a period of 25 minutes. The engine ran rough and there was a vibration through the airframe. Following the test run, the engine was removed from the airframe and disassembled. During the disassembly, wear was noted on all of the camshaft lobes, except the #2 cylinder exhaust valve lobe and the lobe for the #3 and #4 intake valves. It was also noted that the #4 exhaust valve was scored and had heat discoloration two thirds of the way down the valve stem. The #4 exhaust discharge ran cooler than the rest of the cylinders during the engine test run.
PROBABLE CAUSE:THE PARTIAL POWER LOSS DUE TO A STICKING VALVE. FACTORS WERE THE REMAINING WORN LOBES ON THE CAMSHAFT AND THE LACK OF SUITABLE TERRAIN ONTO WHICH A SUCCESSFUL FORCED LANDING COULD BE EXECUTED.

Sources:

NTSB id 20001206X01521


Revision history:

Date/timeContributorUpdates
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

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