Individually Owned: 150,657
Corporate Owned: 137,281
Pensacola Regional Airport
Aircraft Accident/Incident Report
Pensacola, Florida 32504
Saturday, July 6, 1996 14:24 CDT
NTSB Narrative Summary Released at Completion of Accident
During the initial part of its takeoff roll, the airplane experienced an engine failure. Uncontained engine debris from the front compressor front hub (fan hub) of the #1 (left) engine penetrated the left aft fuselage. Two passengers were killed and two others were seriously injured. The takeoff was rejected, and the airplane was stopped on the runway. The fan hub had fractured through a tierod hole and blade slot. Some form of drill breakage or drill breakdown, combined with localized loss of coolant and chip packing, had occurred during the drilling process, creating an altered microstructure and ladder cracking in the fan hub. Drilling damage extended much deeper into hole sidewall material than previously anticipated by P & W. Fatigue cracks initiated from the ladder cracking in the tierod hole and began propagating almost immediately after the hub was put into service in 1990. The crack was large enough to have been detectable during the last fluorescent penetrant inspection at Delta. Delta's nondetection of the crack was caused either by a failure of the cleaning and fluorescent penetrant inspection processing, a failure of the inspector to detect the crack, or some combination of these factors.
NTSB Probable Cause Narrative
the fracture of the left engine's front compressor fan hub, which resulted from the failure of Delta Air Lines' fluorescent penetrant inspection process to detect a detectable fatigue crack initiating from an area of altered microstructure that was created during the drilling process by Volvo for Pratt & Whitney and that went undetected at the time of manufacture. Contributing to the accident was the lack of sufficient redundancy in the in-service inspection program. (NTSB Report AAR-98/01)
Event Information
| Type of Event | Accident |
| Event Date | 7/6/1996 |
| Event Day of the Week | Saturday |
| Time of Event | 1424 |
| Event Time Zone | Central Daylight Time |
| Event City | PENSACOLA |
| Event State | FLORIDA |
| Event Country | -- |
| Zipcode of the event site | 32504 |
| Event Date Year | 1996 |
| Event Date Month | 7 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | PENSACOLA REGIONAL |
| Event Location Nearest Airport ID | PNS |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 121 |
| Weather Briefing Completeness | Full |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1406 Central Daylight Time |
| Direction of event from weather observation facility (degrees) | 200 |
| Weather Observation Facility ID | PNS |
| Elevation of weather observation facility | 121 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 3400 |
| Sky/Lowest/Cloud Conditions | Scattered |
| Sky Condition for Lowest Ceiling | Unknown |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 7 |
| Air Temperature at event time (in degrees celsius) | 32 |
| Dew Point at event time (in degress fahrenheit) | 25 |
| Wind Direction (degrees magnetic) | 210 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 12 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 29 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 2 |
| Injury Total Minor | 3 |
| Injury Total None | 135 |
| Injury Total Serious | 2 |
| Injury Total All | 7 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1696 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Jul 6 1996 12:00AM |
| NTSB Notification Time | 0 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | May 3 2002 3:34PM |
| User who most recently changed record | NTSB\HAMG |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N927DA |
| NTSB Number | DCA96MA068 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | Ground |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | McDonnell Douglas |
| Aircraft Model | MD-88 |
| Aircraft Series Identifier | MD-88 |
| Aircraft Serial Number | 49714 |
| Certified Max Gross Weight | 149500 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 142 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | 22031 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | DELTA AIR LINES INC |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | ATLANTA |
| Aircraft Owner State | GA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 30320 |
| Operator is an individual? | No |
| Operator Name | -- |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | -- |
| Operator State | -- |
| Operator Country | -- |
| Operator Zip code | -- |
| Operator Code | DALA |
| Owner has at least one certificate | -- |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | Yes |
| Departure Airport Code | PNS |
| Departure City | -- |
| Departure State | -- |
| Departure Country | -- |
| Departure Time | 1424 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | ATL |
| Destination City | ATLANTA |
| Destination State | GA |
| Destination Country | USA |
| Specific Phase of Flight | Takeoff |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | May 3 2002 3:34PM |
| User who most recently changed record | NTSB\HAMG |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | 17 |
| Runway Length | 7002 |
| Runway Width | 150 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |