# NTSB DEN00FA078: Douglas DC-8-62F, N990CF, Denver, CO, April 28, 2000 - Type: NTSB accident investigation - Classification: Accident · No injuries · Field investigation · Final report - Date: April 27, 2000, 21:30 local (Apr 28, 2000, 03:30 UTC) - Place: Denver, CO - Coordinates: 39.849308, -104.699798 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.8493&lon=-104.6998&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 5 uninjured - Status: Completed, report April 6, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 49071 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN00FA078 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/49071/pdf - Page: https://openairdocs.org/ntsb/DEN00FA078 ## 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. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - miscellaneous,bolt/nut/fastener/clamp/spring - failure (cause) - bleed air system,lines - disconnected (contributing factor) - nacelle/pylon - pressure excessive (contributing factor) - cooling system,cowling - separation (contributing factor) - fuselage,pressure bulkhead - penetrated ## Analysis The airplane was in cruise flight at 37,000 feet msl. The captain 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. Postlanding 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 stabilator 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 clamp that connected them was missing. The clamp was never located. According to the operator, failure of the clamp would dump high-pressure bleed air into the nacelle, resulting in over-pressurization and separation of the cowlings. 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. ## Factual narrative On April 27, 2000, at 2130 mountain daylight time, a Douglas DC-8-62F, N990CF, was substantially damaged when the number two engine cowling departed the airplane near Denver, Colorado. The airline transport captain and first officer, the commercial pilot flight engineer, and two passengers were not injured. The airplane was owned by Fleet National Bank of Hartford, Connecticut, and was being operated by Emery Worldwide Airlines, Vandalia, Ohio, under Title 14 CFR Part 121. 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. Postlanding examination, by the NTSB Investigator-In-Charge and an FAA Inspector, 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 stabilator 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 blowout panels." ## Aircraft - Registration: [N990CF](https://openairdocs.org/deregistered/N990CF-2002-05-15), registration cancelled 2002-05-15, S/N 46068, built 1969 (OpenAirDocs) - Reported make and model: Douglas DC-8-62F - Registry model: [Douglas DC-8-62](https://openairdocs.org/model/douglas-dc-8-62) (registry code 3021970) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT3D-3&3B](https://openairdocs.org/engine/pratt-whitney-jt3d-3-3b) (registry code 52039, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 46068 - Airframe hours: 51844 - Engines: P&W JT3D-7 19000 lbs thrust turbo fan - Damage: Substantial damage - Flight: Part 121 - Operator: Emery Worldwide Airlines - Registered owner: Fleet National Bank - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, April 13, 2000, 74 hours before - Departed: SEA, SEATTLE, WA - Destination: DAY, DAYTON, OH - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; commercial, flight engineer, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 11,000 total, 5,100 in this make and model, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 110° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 59 °F - Altimeter: 30.00 inHg - Observed at: MLS ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20000427017119I](https://openairdocs.org/incident/20000427017119I), Apr 27, 2000: Doug DC862, Denver, CO, Minor damage. (-23)On April 28, 2000, emery flight 025, enroute form sea to day was over eastern Montana. At approxiamtely 0330Z in cruise at FL370, the crew heard a loud… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.