Narrative:
A Douglas DC-8-62F, N990CF, was substantially damaged when the number two engine cowling departed the airplane near Denver, Colorado. The three flight crew members and two passengers were not injured. Visual meteorological conditions prevailed for the night cross-country flight, which originated from Seattle, Washington, 2 hours 48 minutes before the accident. An IFR flight plan had been filed for the cargo flight that was en route to Dayton, Ohio.
The captain said that they were in cruise flight at 37,000 feet mean sea level (msl). He said that they heard a loud bang and the airplane shook, and they immediately began to lose cabin pressurization. The engine instruments went dead on number two- engine, and they pulled the number two emergency "T" handle. He said that they donned their oxygen masks, began descending, and diverted to Denver. Their landing was uneventful.
Post landing examination of the number two-engine nacelle revealed that the inboard and outboard main engine cowlings had separated from the aircraft. An 18x6 inch hole was found half way up the fuselage (pressure bulkhead), just aft of the left wing; the left horizontal stabiliser was also damaged. Further examination of the engine revealed that the 4 inch-diameter high pressure bleed air duct had separated from the high-pressure relief valve, and the connecting clamp was missing. The clamp was never located.
The wire bundle, which transmitted the number two engine monitoring data to the cockpit, was found cut. There was no evidence of engine fire, or fire in the nacelle cavity.
According to the operator: "when the clamp assembly failed, high pressure bleed air from the 4 inch diameter duct dumped into the area inside of the engine cowlings. The sudden over-pressurization probably expanded the main engine cowlings into the air stream, leading to the loss of the cowlings. The amount of airflow from the high pressurization bleed air duct far exceeds the air discharge capacities of the cowling blow out panels."
PROBABLE CAUSE: "The failure of the clamp that secured the high-pressure bleed air duct to the high-pressure relief valve. Factors were the resulting excessive pressurization of the engine nacelle, and the subsequent separation of the engine cowling."
Forced landing on runway
| Status: | Accident investigation report completed and information captured |
| Date: | Thursday 27 April 2000 |
| Time: | 21:30 |
| Type: |  McDonnell Douglas DC-8-62F |
| Operator: | Emery Worldwide |
| Registration: | N990CF |
| MSN: | 46068/463 |
| First flight: | 1969 |
| Total airframe hrs: | 51844 |
| Crew: | Fatalities: 0 / Occupants: 3 |
| Passengers: | Fatalities: 0 / Occupants: 2 |
| Total: | Fatalities: 0 / Occupants: 5 |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | Denver, CO ( United States of America)
|
| Phase: | En route (ENR) |
| Nature: | Cargo |
| Departure airport: | Seattle/Tacoma International Airport, WA (SEA/KSEA), United States of America |
| Dayton-James Cox Dayton International Airport, OH (DAY/KDAY), United States of America |
A Douglas DC-8-62F, N990CF, was substantially damaged when the number two engine cowling departed the airplane near Denver, Colorado. The three flight crew members and two passengers were not injured. Visual meteorological conditions prevailed for the night cross-country flight, which originated from Seattle, Washington, 2 hours 48 minutes before the accident. An IFR flight plan had been filed for the cargo flight that was en route to Dayton, Ohio.
The captain said that they were in cruise flight at 37,000 feet mean sea level (msl). He said that they heard a loud bang and the airplane shook, and they immediately began to lose cabin pressurization. The engine instruments went dead on number two- engine, and they pulled the number two emergency "T" handle. He said that they donned their oxygen masks, began descending, and diverted to Denver. Their landing was uneventful.
Post landing examination of the number two-engine nacelle revealed that the inboard and outboard main engine cowlings had separated from the aircraft. An 18x6 inch hole was found half way up the fuselage (pressure bulkhead), just aft of the left wing; the left horizontal stabiliser was also damaged. Further examination of the engine revealed that the 4 inch-diameter high pressure bleed air duct had separated from the high-pressure relief valve, and the connecting clamp was missing. The clamp was never located.
The wire bundle, which transmitted the number two engine monitoring data to the cockpit, was found cut. There was no evidence of engine fire, or fire in the nacelle cavity.
According to the operator: "when the clamp assembly failed, high pressure bleed air from the 4 inch diameter duct dumped into the area inside of the engine cowlings. The sudden over-pressurization probably expanded the main engine cowlings into the air stream, leading to the loss of the cowlings. The amount of airflow from the high pressurization bleed air duct far exceeds the air discharge capacities of the cowling blow out panels."
Probable Cause:
PROBABLE CAUSE: "The failure of the clamp that secured the high-pressure bleed air duct to the high-pressure relief valve. Factors were the resulting excessive pressurization of the engine nacelle, and the subsequent separation of the engine cowling."
Accident investigation:
 |
|
Classification:
Loss/opening of engine cowlingForced landing on runway
Sources:
» NTSBPhotos
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Seattle/Tacoma International Airport, WA to Dayton-James Cox Dayton International Airport, OH as the crow flies is 3119 km (1949 miles).
Distance from Seattle/Tacoma International Airport, WA to Dayton-James Cox Dayton International Airport, OH as the crow flies is 3119 km (1949 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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