Date & Time:
Dec 12, 1985 at 1921 LT
Type of aircraft:
Learjet 35
Operator:
Registration:
N723GL
Flight Phase:
Takeoff (climb)
Flight Type:
Executive/Corporate/Business
Survivors:
Yes
Schedule:
College Station - Houston
MSN:
35-107
YOM:
1977
Country:
United States of America
Region:
North America
Crew on board:
2
Crew fatalities:
1
Pax on board:
1
Pax fatalities:
1
Other fatalities:
0
Total fatalities:
2
Captain / Total hours on type:
4000
Aircraft flight hours:
8963
Circumstances:
The aircraft rolled to the right and crashed after a catastrophic (uncontained) failure of the right engine during takeoff for a night flight. The right engine fan rotor disc separated from the hub which damaged the cowling and some disc fragments buried in the fuselage but without damage to the flight controls. The drag created by the loss of thrust and the distorted cowling led to yaw and roll with loss of control of the aircraft. The fan failure propagated from a low grade fatigue crack on the high time fan which was not detected by the visual inspection procedures existing at the time. The manufacturer has since improved the manufacturing and inspection techniques. An AD 86-04-02 was issued on 2/14/86 which deals with fan removal from service according to an operating cycle schedule.
Probable cause:
Occurrence #1: loss of engine power (total) - mech failure/malf
Phase of operation: takeoff - initial climb
Findings
1. (c) compressor assembly, forward fan - fatigue
2. (c) compressor assembly, forward fan - failure, total
3. (c) compressor assembly, forward fan - separation
4. (f) insufficient standards/requirements - manufacturer
----------
Occurrence #2: loss of control - in flight
Phase of operation: takeoff - initial climb
Findings
5. Directional control - not possible - pilot in command
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Occurrence #3: in flight collision with terrain/water
Phase of operation: descent - uncontrolled
Phase of operation: takeoff - initial climb
Findings
1. (c) compressor assembly, forward fan - fatigue
2. (c) compressor assembly, forward fan - failure, total
3. (c) compressor assembly, forward fan - separation
4. (f) insufficient standards/requirements - manufacturer
----------
Occurrence #2: loss of control - in flight
Phase of operation: takeoff - initial climb
Findings
5. Directional control - not possible - pilot in command
----------
Occurrence #3: in flight collision with terrain/water
Phase of operation: descent - uncontrolled
Final Report:
N723GL.pdf90.08 KB
