Kevin J. Renze, Ph.D. Airplane Performance. Elevator Control Authority Investigation FDR data from...

Kevin J. Renze, Ph.D.Kevin J. Renze, Ph.D.

Airplane PerformanceAirplane Performance

Elevator Control Authority Investigation

Elevator Control Authority Investigation

• FDR data from 84 previous flights operated with the accident airplane

• Beechcraft 1900D simulation

• FDR data from 84 previous flights operated with the accident airplane

• Beechcraft 1900D simulation

Elevator Travel RangeElevator Travel Range

-22-20-18-16-14-12-10

-8-6-4-202468

10121416182022

-22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22

ANU ACTUAL ELEVATOR (DEG.) AND

AND

FD

R EL

EVAT

OR (D

EG.)

ANU

BEFORE MAINTENANCECONTROL CHECK

FLIGHT


-22-20-18-16-14-12-10

-8-6-4-202468

10121416182022

-22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22


AND

FD

R EL

EVAT

OR (D

EG.)

ANU

BEFORE MAINTENANCE

FLIGHT TEST

14.7º (AND)

21º (ANU)


-22-20-18-16-14-12-10

-8-6-4-202468

10121416182022

-22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22


AND

FD

R EL

EVAT

OR (D

EG.)

ANU

BEFORE MAINTENANCE

AFTER MAINTENANCE

7º (AND)

SHIFT

FLIGHT TEST

14.7º (AND)

21º (ANU)

21º (ANU)


-22-20-18-16-14-12-10

-8-6-4-202468

10121416182022

-22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22


AND

FD

R EL

EVAT

OR (D

EG.)

ANU

BEFORE MAINTENANCE

AFTER MAINTENANCE

7º (AND)

SHIFT

FLIGHT TEST

14.7º (AND)

21º (ANU)

21º (ANU)

ELEVATOR TRAVEL LOSS

Beechcraft 1900D SimulationBeechcraft 1900D Simulation

• Engineering models provided by RAC

• Implemented in NTSB simulation tools

• Validated against Beechcraft 1900D flight test data

• Engineering models provided by RAC

• Implemented in NTSB simulation tools

• Validated against Beechcraft 1900D flight test data

-20

-15

-10

-5

0

5

10

15

20

-20

-15

-10

-5

0

5

10

15

20

FLIGHT AFTER MAINTENANCE

AIRPLANE NOSE UP

Ele

vato

r (D

egre

es)

Time (Seconds)

FDR ELEVATOR

FLIGHT BEFORE MAINTENANCE

SIMULATION ELEVATOR

AIRPLANE NOSE UP

Ele

vato

r (D

egre

es)

Time (Seconds)

FDR ELEVATOR

SIMULATION ELEVATOR

Beechcraft 1900D Simulation ResultsBeechcraft 1900D Simulation Results

Takeoff Roll

Rotation Climb

Takeoff Roll

Rotation

Climb

SHIFT

Flight 5481 Simulation ResultsFlight 5481 Simulation Results

• The elevator was restricted to 8º downward

• 9.5º downward elevator was needed

• 7º downward elevator needed if CG within limits

• Balance is critical pitch control factor, not weight

• The elevator was restricted to 8º downward

• 9.5º downward elevator was needed

• 7º downward elevator needed if CG within limits

• Balance is critical pitch control factor, not weight

ConclusionsConclusions

• Maintenance changed the pitch control system

• Elevator was restricted to about half its downward travel• FDR data analysis (7º downward)• NTSB simulation (8º downward)

• 9.5º downward elevator needed• 7º downward elevator needed if CG within

limits

• Maintenance changed the pitch control system

• Elevator was restricted to about half its downward travel• FDR data analysis (7º downward)• NTSB simulation (8º downward)

• 9.5º downward elevator needed• 7º downward elevator needed if CG within

limits

Airplane Weight and BalanceAirplane Weight and Balance

• Air Midwest program

• Component load buildup

• Takeoff ground roll analysis

• Air Midwest program

• Component load buildup

• Takeoff ground roll analysis

Flight 5481 Weight and Balance Flight 5481 Weight and Balance

11,000

12,000

13,000

14,000

15,000

16,000

17,000

18,000

0 5 10 15 20 25 30 35 40 45 50 55 60

CENTER OF GRAVITY (%MAC)

AIR

PL

AN

E W

EIG

HT

(L

BS

)

CALCULATED

ACTUAL

APPROVED ENVELOPE

Average Weight ComparisonAverage Weight Comparison

Air Midwest1 FAA Guidance

Component Old (lb) New (lb) Old (lb) Interim (lb)

Passenger and

carry-on bags/ personal items

175 200 185 195

Checked bag 25 30 25 30

Carry-on bag checked planeside

25 20 - -

1 Limited carry-on program1 Limited carry-on program

Improved Weight and Balance Improved Weight and Balance

11,000

12,000

13,000

14,000

15,000

16,000

17,000

18,000

0 5 10 15 20 25 30 35 40 45 50 55 60

CENTER OF GRAVITY (%MAC)

AIR

PL

AN

E W

EIG

HT

(L

BS

)NEW PROGRAM

ACTUAL

APPROVED ENVELOPE

Weight and Balance ConcernsWeight and Balance Concerns

• Average Weight Error Sources – Understated average weights– Heavy bags– Variance in actual weight and weight distribution

• Average weight programs need improvement

• Actual weight and location data could eliminate these errors

• Average Weight Error Sources – Understated average weights– Heavy bags– Variance in actual weight and weight distribution

• Average weight programs need improvement


Pitch Control Assessment Pitch Control AssessmentCenter of Gravity

Elevator Travel

Pitch Control

Pre D6 Flights In Limits Normal Adequate


Elevator Travel

Pitch Control


9 Post D6 Flights In Limits Restricted Critical


Elevator Travel

Pitch Control



Accident Loading, Normal Elevator

Significantly Aft

Normal Marginal


Elevator Travel

Pitch Control




Significantly Aft

Normal Marginal

Beech 1900C Homer, AK 1987

Extremely Aft

Normal Accident


Elevator Travel

Pitch Control




Significantly Aft

Normal Marginal

Beech 1900C Homer, AK 1987

Extremely Aft

Normal Accident

Flight 5481Significantly

AftRestricted Accident

ConclusionsConclusions• Air Midwest’s program did not detect the

significantly aft CG

• Unacceptable errors still exist in average weight programs and require improvements


• The significantly aft CG and restricted elevator resulted in a loss of pitch control

• Air Midwest’s program did not detect the significantly aft CG

• Unacceptable errors still exist in average weight programs and require improvements


• The significantly aft CG and restricted elevator resulted in a loss of pitch control

Kevin J. Renze, Ph.D. Airplane Performance. Elevator Control Authority Investigation FDR data from...

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