kevin j. renze, ph.d. · pitch control elevator travel center of gravity. pitch control assessment....
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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
AN
D F
DR
EL
EV
AT
OR
(D
EG
.)A
NU
BEFORE MAINTENANCECONTROL CHECK
FLIGHT
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
AN
D F
DR
EL
EV
AT
OR
(D
EG
.)A
NU
BEFORE MAINTENANCE
FLIGHT TEST
14.7º (AND)
21º (ANU)
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
AN
D F
DR
EL
EV
AT
OR
(D
EG
.)A
NU
BEFORE MAINTENANCE
AFTER MAINTENANCE
7º (AND)
SHIFT
FLIGHT TEST
14.7º (AND)
21º (ANU)
21º (ANU)
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
AN
D F
DR
EL
EV
AT
OR
(D
EG
.)A
NU
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
-20-15-10-505
101520
-20-15-10-505
101520
FLIGHT AFTER MAINTENANCE
AIRPLANE NOSE UP
Elev
ator
(Deg
rees
)
Time (Seconds)
FDR ELEVATOR
FLIGHT BEFORE MAINTENANCE
SIMULATION ELEVATOR
AIRPLANE NOSE UP
Elev
ator
(Deg
rees
)
Time (Seconds)
FDR ELEVATOR
SIMULATION ELEVATOR
Beechcraft 1900D Simulation ResultsBeechcraft 1900D Simulation Results
Takeoff Roll
Rotation Climb
Takeoff Roll
RotationClimb
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
Kevin J. Renze, Ph.D.Kevin J. Renze, Ph.D.Airplane PerformanceAirplane Performance
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 BalanceFlight 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
PLA
NE
WEI
GH
T (L
BS)
CALCULATEDACTUAL
APPROVED ENVELOPE
Average Weight ComparisonAverage Weight Comparison
30253025Checked bag
--2025Carry-on bag checked planeside
195185200175Passenger andcarry-on bags/ personal items
Interim (lb)Old (lb)New (lb)Old (lb)ComponentFAA GuidanceAir Midwest1
1 Limited carry-on program1 Limited carry-on program
Average Weight ComparisonAverage Weight Comparison
30253025Checked bag
--2025Carry-on bag checked planeside
195185200175Passenger andcarry-on bags/ personal items
Interim (lb)Old (lb)New (lb)Old (lb)ComponentFAA GuidanceAir Midwest1
1 Limited carry-on program1 Limited carry-on program
Improved Weight and BalanceImproved 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
PLA
NE
WEI
GH
T (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
• Actual weight and location data could eliminate these errors
Pitch Control AssessmentPitch Control Assessment
AdequateNormalIn LimitsPre D6 Flights
Pitch ControlElevator Travel
Center of Gravity
Pitch Control AssessmentPitch Control Assessment
CriticalRestrictedIn Limits9 Post D6 Flights
AdequateNormalIn LimitsPre D6 Flights
Pitch ControlElevator Travel
Center of Gravity
Pitch Control AssessmentPitch Control Assessment
MarginalNormalSignificantly Aft
Accident Loading, Normal Elevator
CriticalRestrictedIn Limits9 Post D6 Flights
AdequateNormalIn LimitsPre D6 Flights
Pitch ControlElevator Travel
Center of Gravity
Pitch Control AssessmentPitch Control Assessment
AccidentNormalExtremely Aft
Beech 1900C Homer, AK 1987
MarginalNormalSignificantly Aft
Accident Loading, Normal Elevator
CriticalRestrictedIn Limits9 Post D6 Flights
AdequateNormalIn LimitsPre D6 Flights
Pitch ControlElevator Travel
Center of Gravity
Pitch Control AssessmentPitch Control Assessment
AccidentRestrictedSignificantly AftFlight 5481
AccidentNormalExtremely Aft
Beech 1900C Homer, AK 1987
MarginalNormalSignificantly Aft
Accident Loading, Normal Elevator
CriticalRestrictedIn Limits9 Post D6 Flights
AdequateNormalIn LimitsPre D6 Flights
Pitch ControlElevator Travel
Center of Gravity
ConclusionsConclusions• Air Midwest’s program did not detect the
significantly aft CG
• Unacceptable errors still exist in average weight programs and require improvements
• Actual weight and location data could eliminate these errors
• 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
• Actual weight and location data could eliminate these errors
• The significantly aft CG and restricted elevator resulted in a loss of pitch control
Kevin J. Renze, Ph.D.Kevin J. Renze, Ph.D.Airplane PerformanceAirplane Performance