- Date
- March 31, 1993, 12:34 local (16:34 UTC)
- Place
- Anchorage, AK
- Injuries
- 5 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N473EVBoeing 747-121
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 10, 1994
- Report
- Board-adopted at Board Meeting
- Investigation class
- Class 1
- NTSB office
- Major Investigations Division
- Safety recommendations
- Yes
- FAA report
- 19930331007479A
- Case key
- 10973
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The lateral separation of the no. 2 engine pylon due to an encounter with severe or possibly extreme turbulence that resulted in dynamic multi-axis lateral loadings that exceeded the ultimate lateral load-carrying capability of the pylon, which was already reduced by the presence of the fatigue crack near the forward end of the pylon's forward firewall web.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
Shortly after takeoff from Anchorage, the airplane flew into an area of severe turbulence, while climbing through an altitude of about 2000 feet. The number 2 engine and engine pylon separated from the airplane. The flightcrew declared an emergency and the flight return to Anchorage, where an uneventful landing was accomplished. The investigation revealed that a strong easterly wind interacted with mountains east of Anchorage, which produced mountain wave activity. The aircraft encountered severe or possibly extreme turbulence. There was evidence that this resulted in dynamic multi-axis lateral loadings that exceeded the ultimate lateral load-carrying capability of the number 2 engine pylon, which had already been reduced by the presence of a fatigue crack near the forward end of the pylon's forward firewall web.
Factual narrative
See NTSB blue cover aviation accident report AAR-93-06 for further information.
Aircraft
- Registration
- N473EV
- Reported as
- Boeing 747-121
- Category
- Airplane
- Serial number
- 19657
- Airframe hours
- 18,370
- Engine
- P&W JT9D-7D, 45,500 lbs thrust, turbo fan
- Damage
- Substantial damage
- Flight
- Part 129
- Operator
- Japan Airlines
- Registered owner
- Evergreen International
- Last inspection
- Continuous airworthiness · March 3, 1993 · 48 hours before
- Departed
- ANC
- Destination
- ORD · Chicago, IL
- Flight plan
- IFR
- Airport
- ANC · Anchorage Intl, runway 6R, 10,897 × 150 ft
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 42
- Certificates
- Commercial, Airline transport
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Helicopter, Airplane
- Medical
- Class 1, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 10,000 total · 750 in this make and model · 8,000 as pilot in command · 138 in the last 90 days · 61 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 90° at 7 knots
- Visibility
- 60 statute miles
- Lowest ceiling
- 8,000 ft overcast
- Temperature
- 48 °F, dew point 21 °F
- Altimeter
- 29.00 inHg
- Observed at
- ANC
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.