# NTSB ATL93MA055: Lockheed L382E-44K-20, N130X, Marietta, GA, February 3, 1993

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Major investigation · Final report
- Date: February 3, 1993, 13:27 local (18:27 UTC)
- Place: Marietta, GA
- Location: 33.9144° N, 84.5142° W: Placed by OpenAirDocs at DOBBINS ARB (MGE), within about a mile (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=33.9144&lon=-84.5142&mi=10
- Phase of flight: [Other](https://openairdocs.org/ntsb-phases/800) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 7 fatal
- Status: Completed, report March 18, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 8743
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL93MA055
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8743/pdf
- Page: https://openairdocs.org/ntsb/ATL93MA055

## Probable cause

DISENGAGEMENT OF THE RUDDER FLY-BY-WIRE FLIGHT CONTROL SYSTEM RESULTING IN A TOTAL LOSS OF RUDDER CONTROL CAPABILITY WHILE CONDUCTING GROUND MINIMUM CONTROL SPEED TESTS. THE DISENGAGEMENT WAS A RESULT OF THE INADEQUATE DESIGN OF THE RUDDER'S INTEGRATED ACTUATOR PACKAGE BY ITS MANUFACTURER; THE OPERATOR'S INSUFFICIENT SYSTEM SAFETY REVIEW FAILED TO CONSIDER THE CONSEQUENCES OF THE INADEQUATE DESIGN TO ALL OPERATING REGIMES. A FACTOR WHICH CONTRIBUTED TO THE ACCIDENT WAS THE FLIGHT CREW'S LACK OF ENGINEERING FLIGHT TEST TRAINING.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of control - on ground/water, other
  - flt control syst,rudder control - inadequate (cause)
  - acft/equip,inadequate design, manufacturer (contributing factor)
  - inadequate substantiation process,insuff review, company/operator mgmt (cause)
  - flt control syst,rudder - disengaged (cause)
  - directional control - not possible, pilot in command (cause)
  - procedures/directives - not followed, pilot in command
  - inadequate training, company/operator management (contributing factor)
- Loss of control - in flight, takeoff - initial climb
  - lift-off - performed, pilot in command
  - aircraft control - not possible, pilot in command (cause)
  - stall/spin - inadvertent, pilot in command
- In flight collision with terrain/water, takeoff - initial climb

## Analysis

THE ACFT WAS DESIGNED & USED AS THE COMPANY'S ENGINEERING TEST BED. AN EVALUATION OF THE FLY-BY-WIRE RUDDER ACTUATOR & GROUND MINIMUM CONTROL SPEED (VMCG) WAS BEING CONDUCTED. DURING THE FINAL HI-SPEED GROUND TEST RUN, THE ACFT ABRUPTLY VEERED LEFT & BECAME AIRBORNE. IT ENTERED A LEFT TURN, CLIMBED TO ABOUT 250 FT, DEPARTED CONTROLLED FLT & IMPACTED THE GRND. INVESTIGATION REVEALED A DESIGN FEATURE IN THE RUDDER ACTUATOR THAT REMOVES HYD PRESSURE WITHIN THE ACTUATOR IF THE RUDDER POSITION COMMANDED BY THE PILOT EXCEEDED THE ACTUAL RUDDER ACTUATOR POSITION FOR A SPECIFIED TIME, AND THE RUDDER AERODYNAMICALLY TRAILS. THE ACTUATOR PREVIOUSLY DISENGAGED IN FLT. THE COMPANY DID NOT CONDUCT A SYSTEM SAFETY REVIEW OF THE RUDDER BYPASS FEATURE & ITS CONSEQUENCES TO ALL FLT REGIMES, NOR OF THE VMCG TEST. THE FLT TEST PLAN SPECIFIED THAT ENGINE POWER BE RETARDED IF THE RUDDER BECAME INEFFECTIVE. NEITHER PLT HAD RECEIVED TRAINING AS AN EXPERIMENTAL TEST PLT. THE COMPANY ALLOWED EXPERIMENTAL FLT TESTS AT A CONFINED, METROPOLITAN ARPT.

## Aircraft

- Registration: [N130X](https://openairdocs.org/deregistered/N130X-1997-02-05), registration cancelled 1997-02-05, S/N 4412 (OpenAirDocs)
- Reported make and model: LOCKHEED L382E-44K-20 (L382E-44K-)
- Registry model: [Lockheed 382E-44K-20](https://openairdocs.org/model/lockheed-382e-44k-20) (registry code 526414X) (OpenAirDocs)
- Category: Airplane
- Serial number: 4412
- Airframe hours: 6708
- Engines: ALLISON 501-M71K 5250 horsepower turbo prop
- Damage: Destroyed
- Fire: On-Ground
- Flight: Part 91
- Operator: Lockheed Aero. Systems Co.
- Registered owner: Lockheed Aero. Systems Co.
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Continuous airworthiness, March 5, 1991, 29 hours before
- Departed: MGE
- Destination: MGE
- Flight plan: Company VFR
- Airport: MGE, Dobbins Afb, runway 11, 10,000 × 300 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; airline transport, flight instructor, flight engineer; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 7,658 total, 1,260 in this make and model, 5,276 as pilot in command, 74 in the last 90 days, 16 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 130° at 3 knots
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 50 °F, dew point 10 °F
- Altimeter: 30.00 inHg
- Observed at: MGE, 1 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19930203001389A](https://openairdocs.org/incident/19930203001389A), Feb 3, 1993: Lkheed 382E, Marietta, GA, Destroyed, 7 fatal. Crashed after takeoff on test flight with engine out evaualating experimental fly by were control system.

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.

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