ASN logo
ASN Wikibase Occurrence # 133129
Last updated: 27 September 2019
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information. If you feel this information is incomplete or incorrect, you can submit corrected information.

Date:12-JAN-1995
Time:17:30
Type:Silhouette image of generic H269 model; specific model in this crash may look slightly different
Hughes 269C
Owner/operator:Usda - Aphis
Registration: N796
C/n / msn: 690804
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Dumont, TX -   United States of America
Phase: Landing
Nature:Unknown
Departure airport:
Destination airport:
Investigating agency: NTSB
Narrative:
On January 12, 1995, approximately 1730 central standard time, a Hughes 269C, N796, was destroyed during a forced landing near Dumont, Texas. The helicopter, owned and operated by the U.S. Department of Agriculture, was on a local public use flight. There was no flight plan filed and visual meteorological conditions prevailed. Neither the pilot, nor the gunner were injured.

The pilot reported in a written statement that he was at an altitude of "about 40 feet above ground level," maneuvering south at "about 30 knots" herding some "hogs." The pilot further stated that, he experienced severe vibrations, to a level that interfered with his vision.

The pilot then began "milking the collective" in an attempt to regain power, in an attempt to land. The pilot further stated that he determined that he "did not have enough airspeed to flare."

According to local law enforcement officials and the pilot the aircraft struck the ground in a "straight and level attitude;" however, "the helicopter landed hard," bounced 13 feet, and rolled over onto its right side.

An examination of the engine revealed that the #3 cylinder connecting rod bearing cap bolts had fractured resulting in a catastrophic failure of the bearing cap and piston. The connecting rod arm, cap and corresponding nuts and fractured bolts from cylinder #3 were forwarded to the Safety Board's materials laboratory for further metallurgical examination.

NTSB Metallurgist's Factual Report No.95-98 states "Scanning electron microscopic examination of all bolt fractures revealed that the fractured areas that were located adjacent to the outside diameter contained mechanical damage that obliterated the original fracture features. However, the remaining portion of the fracture surface at the center of each bolt contained no damage and exhibited ductile dimple fracture features that are typical of an overstress separation." (All references to cylinder #4 in the report should correctly read cylinder #3.)

The nuts and connecting rod bolts had markings, chemical compositions, microstructure, hardness, and thread configurations consistent with those specified by the manufacturer.

The aircraft and the tested components were returned to the operator following completion of the investigation.

(This narrative was rewritten March 18, 1997 by Joel K. Ryan, Senior Air Safety Investigator, Regional Operations and General Aviation Division, Office of Aviation Safety. The original narrative contained details of a metallurgical examination of components from another accident, and should be disregarded. This error was brought to the Safety Board's attention in a letter from the U.S. Department of Agriculture (USDA) dated February 19, 1997, and the letter has been added to the report.)
PROBABLE CAUSE:THE LOSS OF ENGINE POWER DUE TO OVERSTRESS FRACTURES OF THE #3 CYLINDER CONNECTING ROD CAP BOLTS. THE ORIGIN OF THE FRACTURES COULD NOT BE DETERMINED.

Sources:

NTSB id 20001207X02854


Revision history:

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

Corrections or additions? ... Edit this accident description