Cessna Model 162 (Skycatcher) Spin Compliance/Safety Lessons Learned

1
Cessna Model 162 (Skycatcher)Spin
Compliance/Safety Lessons Learned
C. Dale Bleakney (M) Cessna Engineering Flight
Test
2
Introduction What is an LSA?

• ASTM 2245-xx
• Max gross TO weight 1320 lbs
• Min useful load - 430 lbs
• Vs min - 45 KCAS
• Vh max - 120 KCAS
• SE, fixed gear, fixed pitch prop

3
Cessna LSA History
Program Launch Friday, January 13, 2006
Proof of Concept 1st Flight Friday,
October 13, 2006 Prototype 1st Flight
March 7, 2008 Wichita Built P1 1st Flight
April 30, 2008 P1 Production No. 1
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• Model 162 Final Configuration

Wing Span 30 ft
Wing Chord 4 ft

Cabin Width 44.3 in
Flaps 0 Stall 44 KCAS
Flaps 40 Stall 40 KCAS

Usable Fuel 24 gal
5
Instrument Panel
6
Spin Program Overview
In 1980, the US Supreme Court concluded that
"Safe" is not the equivalent of "risk-free."

• LSA Spin Testing Goal Safe, Thorough, Efficient

• ASTM 4.5.9
• .(4) For the flaps-extended condition, the flaps
  may be retracted during recovery.
• 14 CFR 23.221
• .. For the flaps-extended condition, the flaps
  may be retracted during the recovery but not
  before rotation has ceased.
• The rules are technically identical, Therefore
• Spin matrix was defined using FAA Advisory
  Circular 23-8B
• 352 spin conditions

7
Safety Equipment/Process

• First flight
• Chute Helmet
• Chase aircraft w/video
• Special Inspection
• First Flight Readiness Review (FFRR)
• Envelope expansion
• Chute Helmet
• Chase aircraft
• Stalls
• Chute, Helmet, BRS (Aft cg)
• Spins
• BRS, Chute, Helmet
• Chase aircraft w/video
• Spin FFRR

8
Spin Program Weather/Test Constraints Before
1st Spin Event
Weather Ceiling MIN 10,000 feet Surface
Winds MAX 10 knots with 5 knot gusts (chute
limits) Spins per sortie No MAX - BUT
fatigue will be watched Crew Rest MAX - 5
flying days per week NO work or flights on
Sunday
9
Spin Matrix and Buildup Program Before 1st
Spin Event
Spin Matrix Buildups (¼ , ½, 1 turn) Fwd cg,
idle power Normal - flaps - up / down Turning -
flaps - up / down Abused - flaps up / down
Repeat with power on - Buildup to MCP Repeat
at aft cg - Idle, then buildup to MCP
10
Safety Systems Overview

• Crew Entry/Egress
• Removable Door 2 action
• Procedure practiced before 1st flight
• Spin Chute (Options)
• BRS Whole Airplane Chute CHOSEN
• Tail mounted airplane spin chute NOT CHOSEN

11
Spin Event No. 1 September 18, 2008

• BUILDUP
• Spins Successfully Completed
• Fwd cg Idle/MCP
• Fwd cg MCP abused (ailerons with)
• Event SPIN MCP, ailerons against 3 turns
• KEY FACTS
• 143 Successful spins completed
• Key spin characteristics identified
• All spins were ASTM and 23.221 compliant
• Redundant safety systems and safety discipline -
  ALL important

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Spin Event No. 1 - Lessons Learned

• Safety Systems
• BRS Spin Chute - Did not deploy
• Rotation rates and spin attitude contributed to
  improper rocket trajectory and failure
• Changed BRS parachute installation design
• Door Jettison - Dual action door delayed bailout
• Other
• Buildups - Did not forecast event

13
Risk Mitigation/Event analysis Post Event
No.1

• Internal Review
• Flight Test
• Project / Advanced Design
• Outside Assistance
• Former Cessna Test Pilots
• Retired Cessna Aero / Advanced Design
• BIHRLE
• NTPS

14
Post Spin Event No. 1BRS Design Changes
OLD Canister Type Installation
NEW Bed Mount Installation
Parachute
Actuation Handle

• Soft Pack Design No Canister
• Parachute Bag - Oriented horizontally and near
  window
• Rocket aft of parachute - Close proximity to
  window. No way it will catch on anything on the
  way out.
• Cessna designed truss
• Supports both parachute and rocket
• Built in deflectors/guides

Rocket
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Post Event No. 1 - Door Release Changes
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Post-Event No. 1 - Bihrle Spin Tunnel testing

• Power model updated
• Predicted delayed spin recovery
• Now matched event No. 1 spin
• New vertical stabilizer w/ ventral
• Spin tunnel data - No unrecoverable spin modes

17
Safety Equipment/Process

• Spin Briefings (Before and after 1st Event)
• Include standard test card items
• FTE monitors air-to-air frequency
• Standard debrief, data review, and
  characteristics review
• Missing elements (Lessons learned after 1st
  Event)
• Telemetry
• Ground crew at spin sight
• Instrumentation
• Control positions
• Body angle of attack
• Real-time pilot feedback

18
Revised Spin Matrix Post Event No. 1

• Buildup redefined (look at aft cg earlier)
• Idle fwd cg, then aft cg
• then,
• MCP fwd cg, then aft cg
• Note 2000 rpm to MCP (100 rpm at a time)
• 28 to 33 MAC (1 at a time)

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Spin Videos Mod 1 Configuration

• Idle, Flaps Up, Right

• Idle, Flaps 10, Left

20
Risk Mitigation Post Event No. 1

• SAME
• Chase Aircraft
• Spin Chute BRS
• Personal safety equipment
• Brief and debrief
• NEW
• Fly the spin aero simulator before each new
  configuration
• Go/No go as part of pre-flight brief
• Post spin discussion of characteristics-to-simulat
  or correlation
• Detailed characteristics discussions with Flight,
  Aero, Safety
• NO-GO decision is okay Proceed with caution
• Same as before but with increased emphasis
• High definition video for post-spin analysis
• Detailed flight reports to the Chief Pilot,
  Safety to independently assess positive and
  negative characteristics of each spin before we
  proceed.

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Spin/Stall Progress Chart
We are now here
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Spin Event No. 2 - 3/19/2009

• COMM antenna damaged during BRS deployment
• No communication with chase airplane
• Rotation would not stop until engine shutdown
• Pilot Door Jettison Failed
• (Door opened but would not jettison)
• BRS saved the Pilot Impact still substantial
• (approx. 1600 fpm)

23
Tail Change No. 2
Original design

• Original tail (Mar 08)
• Rev 1 tail (Sep 08)
• 20 larger vertical tail
• 10º less rudder sweep
• Removed dorsal fin
• Shielded rudder horn (directional stability)
• Added ventral fin (not shown)
• Rev 2 tail (V4) (Mar 09)
• Increased rudder span
• Ventral moved further aft
• Maximum UP elevator changed from 30 to 22

Rev 1 Design
Rev 2 (V4) Design
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Spin Compliance Completion Plan

• Check Stability and Control/Stalls
• Look for max AOA change
• Reduced max elevator travel (from 30 to 22)
• Power-on stall checked lower AOA/better
  characteristics
• Power-off stall speed checked - still ASTM
  compliant
• Spin Compliance
• New spin chute Aft cg testing only (due to aft
  truss/chute mount)
• New spin matrix (with buildup)
• Redo critical case spins without spin chute/with
  BRS

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Post Event No. 2 Safety/Flight Procedure Changes

• Check Door Release, then re-attach before every
  spin flight
• Maximum of 12 spins per sortie.
• Maximum of 2 sorties per day
• 1 spin pilot Pick up on subtle cues between
  spins
• Early morning flights only reduce pilot fatigue
• Real time feedback from telemetry room on
  entry/recovery on every spin

26
Spin Compliance Matrix (Post No. 2)

• Original Spin Matrix
• 352 Total Spins
• Fwd then aft cg
• Idle then MCP Power
• Turning over-the-top/under-the-bottom
• Abused ailerons with/against
• Remaining untested spins (with spin chute)
• 92 Total Spins
• Aft cg Normal
• Aft cg Turning
• Aft cg Abused (ailerons with, ailerons against,
  Idle/MCP)
• Final Spins (without spin chute, with BRS)
• Aft cg Normal (IDLE), Normal (MCP)
• MCP Abused (ailerons against) (Problem Spin)

27
Spin Video Final (Flaps 10, MCP, abused , Left
, Ail Against)

• With spin chute

• Without spin chute

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Spin/Stall Progress Chart
FINISHED 7/17/2009
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Spin Event Summary

• September 18, 2008 (28 MAC) (Event No. 1)
• BRS failure, Pilot bailed out
• March 12, 2009 (30 MAC) (3 turn recovery)
• Analyzed and thought to be caused by distributed
  ballast
• March 19, 2009 (32 MAC) (Event No. 2)
• (28, 30, 31 MAC successfully completed with
  new ballast configuration)
• 32 MAC recovery not seen after approx 3 turns
• BRS deployed
• Communication antenna lost
• Jettison malfunctioned
• Door release malfunctioned
• Pilot rode airplane to ground
• minor injuries to pilot
• damage to airplane most damage was after impact
• July 17, 2009 (32 MAC) Spins successfully
  completed (with and without spin chute)
• Stall and spin characteristics significantly
  improved

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Summary of Lessons Learned

• Get recent spin practice in a similar airplane
• Spin Tests should be done last - Final aero
  configuration
• Look for excess flight control travels and limit
  them as necessary
• Watch for subtle clues. Stall characteristics
  were a big clue.
• NO two airplanes and NO two spins are identical
  (snowflake effect)
• Safety systems must be robust. (Video)
• TM data with experienced pilot feedback was very
  helpful
• ¼ and ½ turn spin buildup did not predict 1 turn
  behavior
• However, it does acclimate and tune the pilot

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162 Program - Interesting Statistics

• Are you superstitious ???
• LSA Program go Friday, Jan 13, 2006
• POC First flight Friday, October 13, 2006
• First POC cross-country AOPA, Palm Springs, CA
• Flight 13, 1300 NM, took 13 hours
• Spins
• First Proto spin event, Spin 13, Thur, 9/18/08
• Second P1 spin event, Spin 13, Thur, 3/19/09
• Final P1 spin flight, Flight 169 (13 squared)
• No more than 12 spins a day were done with the
  version 2 tail.
• Dont give the big guy a free shot superstition
  or not

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Questions?
Fun at Mach 0.162
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Post Event No. 1Aerodynamic Configuration Changes
Original Proto configuration
Post Event No. 1 configuration

1. Dorsal removed
2. Ventral added
3. Vertical stabilizer chord increased
4. Vertical stabilizer sweep angle decreased

34
Spin Video MCP Abused (Final W/O Spin Chute)

• Flaps 10, MCP, Left Spin, Ailerons Against w/o
  chute

35
Post Spin Event No. 1 - BRS Design Changes
(Details on Next Slide)
OLD Canister Type Installation
NEW Soft pack Installation
36
Bihrle Testing - Post-Event No. 2

• Bihrle Test Matrix
• Baseline with flaps 10
• Baseline plus dorsal (Event configuration)
• Three new vertical stabilizers (20 area)
• Baseline vertical 5-in chord extension (V1)
• New vertical with 10-deg sweep reduction (V4)
• New vertical with zero sweep (V5)
• Vented elevator
• Horizontal stabilizer moved aft
• Additional aileron deflections
• Additional down elevator deflection
• Conclusion
• Selected V4 with/without ventral for simulation
  (see next slide)

37
Post Event No. 1Aerodynamic Configuration Changes
Vertical Stabilizer Changes
V1
V4
Thorough!!
  Area (ft2) LE Sweep (deg) HL Sweep (deg) Rudder/Stabilizer Chord Ratio
Stabilizer V1 8.7 42.9 31.6 0.50
Stabilizer V4 10.4 37.3 21.6 0.40
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Spin Video Normal Spin

• Rev 1 Configuration Flaps Up, Idle, Left Spin

39
Spin Video Idle, Normal Spin

• Mod 1 Configuration Flaps Up, Left Turn (Note
  Entry)

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Spin Event No. 2 - 3/19/2009

• Potential Causes
• Change in perceived AOA at stall/spin entry Too
  much elevator??
• BRS Spin Chute Deployed but would not jettison
• Rotation rate, spin attitude, inability to
  jettison BRS
• High rotation rate caused risers to twist and
  increased friction in release pin attachment
• Friction forces caused cable stretch pilot
  unable to generate enough force to pull the
  release pin

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Stall/Spin Progress Chart
Over 600 stalls completed before the first spin
We are here
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Spin/Stall Progress Chart
We are here
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Spin Video MCP Abused Spin

• Mod 1 Configuration Flaps Up, Left, MCP Ailerons
  Against

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BRS Installation (Before 1st Event)
Actuation Handle
Safe
45
Spin Program Schedule Before 1st Spin Event

• Efficient
• Test Team (Pilots share spin sorties approx.
  50/50)
• Dale Bleakney Project Pilot
• Bob Newsome Contract Pilot (former T-6A Test
  Pilot, and spin pilot)
• Bob Rice Assistance flying spins after first
  event
• Andrew Thorson FTE (in chase airplane)
• Ahmed Mohamed FTE (ground data analysis)
• Sortie Generation Rate
• 2 3 sorties per day
• Spin Pilot/Chase Pilot alternate - Reduce fatigue

46
162 Configuration Change Summary
September 2008 Original Configuration
March 2009 Rev 1 Configuration Post Event No. 1

1. Dorsal removed
2. Ventral fin added
3. Vertical stab chord increased
4. Vertical sweep angle decreased

June 2009 Rev 2 Configuration Post Event No. 2

1. Rudder extended
2. Ventral fin move aft
3. Ailerons geared (reduce adverse yaw)
4. Up elevator reduced from 30 to 22 (Significant)

47
Aileron Change Reduced Adverse Yaw
Pre 3-19-2009 aileron configuration 20 up/ 15
down
Post 3-19-2009 aileron configuration 20 up/ 5
down (less adverse yaw)
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Summary Lessons Learned - 2

• Safety
• Spin chutes are proven technology. Design them
  in at the beginning
• Spin tests should be done last in a program after
  all aero data are gathered. Otherwise, you may
  end up repeating the spin tests.
• Get recent spin practice in a similar airplane
• NO two airplanes and NO two spins are identical
  (snowflake effect)
• NO covenants with past programs. There may not
  be a correlation.
• Watch for subtle clues. Stall characteristics
  were a big clue.
• Reluctant to reduce up elevator due to stall
  speed impact - BIG
• Safety systems MUST be robust.
• TM data - essential.
• Experienced pilot feedback from TM - invaluable.

49
Model 162 Configurations
Pre-September 2008 (Original)
Post-September 2008 (Event No. 1) Increased
vertical, added ventral
Post-March 2009 (Event No. 2) (Final) Ventral
Moved Aft, Rudder Extended Elevator UP Reduced,
Aft cg limit Reduced, Ailerons re-geared
50
Compliance Spin Test Status

• Completed
• Power Off
• Fwd/aft cg wings level
• Fwd/Aft cg turning
• Fwd/aft cg abused controls
• Power On
• Fwd/aft cg wings level
• Incomplete Conditions
• Power On Abused (Aft cg)
• Power On Turning (Aft cg)

51
Ventral Variants
Small ventral
Large ventral
Large ventral installed at a more aft location on
the airplane is a potential option in work
52
Spin Test Status

• Stability Control, Dive, Stall, Performance
  Testing Complete
• Spins - 241 Conditions complete
• Power Off Complete
• Fwd/aft cg wings level
• Fwd/Aft cg turning
• Fwd/aft cg abused controls
• Power On Complete
• Fwd cg wings level
• Spins Remaining 111 Conditions
• MCP Aft cg - wings level
• Turning (Fwd and Aft cg)
• Abused (Fwd and Aft cg)

53
Flight Test Data
Spin Comparison Summary
CG Power Flaps Rudder Aileron Flight Spin Spin Rate (deg/s) Spin Rate (deg/s) Difference From Baseline
CG Power Flaps Rudder Aileron Flight Spin Bef Recovery Input Aft Recovery Input Difference From Baseline
32 MCP 10 Left Right 140 13 92 216 -
28 MCP 10 Left Right 135 14 111 166 CG
31 MCP 10 Left Right 139 13 104 154 CG
32 2200 10 Left Right 140 12 98 196 Power
32 MCP 0 Left Right 140 10 94 174 Flaps
32 MCP 10 Left Neutral 132 7 97 193 Aileron
32 MCP 0 Right Left 140 11 93 113 Right Spin
In each of the following slides, the event spin
data are shown as solid lines, and the comparison
spin data are shown as dashed lines. In each
slide, one variable is changed from the event
spin.
54
Flight Test Data
CG31, MCP, Flaps10, Left Rudder, Right Aileron
55
Flight Test Data
CG 32, 2200 RPM, Flaps 10, Left Rudder, Right
Aileron
56
Flight Test Data
CG32, MCP, Flaps0, Left Rudder, Right Aileron
57
Flight Test Data
CG 32, MCP, Flaps10, Left Rudder, Neutral
Aileron
58
Flight Test Data
CG32, MCP, Flaps 0, Ailerons Against
Spin (Solid-LineLeft Spin, Dashed-LineRight
Spin)
59
Agenda Detail

• Airplane Configuration
• Review of SkyCatcher configurations flown to date
• Comparison between SkyCatcher and Cessna 152
• Geometry
• Wing geometry
• Tail volume coefficients
• Aileron to wing area ratio
• Rudder to vertical tail area ratio
• Elevator to horizontal tail area ratio
• Flap to wing area ratio
• Mass properties comparison

60
Backup Slides
LSA Geometric Comparisons
  Cessna SkyCatcher Cessna 152 Flight Design CTSW Remos GX Tecnam P92 Eaglet
Fore/Aft Length Ratio 0.42 0.41 0.40 0.40 0.42
Engine Pitch (deg) 4 0 5   0
Forward CG 26.0 23.7 32.5 18 20
Aft CG 32.0 30.2 40.6 31 33
Elevator Chord Ratio 0.40 0.41 1 0.44 1
Horizontal Tail Volume Coefficient 0.55 0.46 0.52 0.66 0.47
Rudder Chord Ratio 0.4 0.4 .5 .32 0.35
Vertical Tail Volume Coefficient 0.038 0.032 0.040 0.046 0.052
Aileron Chord Ratio 0.20 0.19 0.21 0.15 0.23
Aileron Flapped Area Ratio 0.32 0.50 0.31 0.43 0.40
Flap Flapped Area Ratio 0.49 0.38 0.53 0.52 0.45
Wing Loading 11.0 10.4 12.3 11.2 10.2
61
Backup Slides
LSA Geometric Comparisons
  Cessna SkyCatcher Cessna 152 Flight Design CTSW Remos GX Tecnam P92 Eaglet
Ventral Area (ft2) 1.1 0 5 2 0
VT/Rudder below Horizontal Yes Yes No No No
MTOW (lbs) 1320 1670 1320 1320 1320
S wing (ft2) 119.9 160.0 107 118 129
mac (in) 48.0 59.0 46 50 55
b wing (in) 359.8 400.0 336 366 342
dihedral wing (deg) 1.5 1.0 1.7   1.5
S horizontal (ft2) 22.2 28.5 18 22 21
horizontal tail arm (in) 142.9 154.0 144 173 157
S vertical (ft2) 10.4 12.5 10 12 15
vertical tail arm (in) 159.1 165.0 146 168 153
total aileron area (ft2) 7.6 17.9 7 8 11
elevator area (ft2) 8.8 11.3 18 10 21
rudder area (ft2) 4.8 6.1 4 3 4
62
Model 162/152 Comparison
Geometry
  Model 162 Model 152
Horizontal Stabilizer Area (ft2) 22.15 28.52
Elevator Area (ft2) 8.80 11.30
Elevator Area Ratio 0.40 0.40
Elevator Chord Ratio 0.40 0.41
Horizontal Tail Volume Coefficient 0.55 0.46
Vertical Stabilizer Area (ft2) 10.44 12.45
Rudder Area (ft2) 4.78 6.10
Rudder Area Ratio 0.46 0.49
Rudder Chord Ratio 0.40 0.40
Vertical Tail Volume Coefficient 0.039 0.032
63
Model 162/152 Comparison
Mass Properties
  152 Full Fuel, MTOW 162 Flight 140
Weight (lb) 1670 1351
Wing Loading (lb/ft2) 10.4 11.3
Ixx (slugft2) 706 599
Iyy (slugft2) 703 625
Izz (slugft2) 1220 1077
Ixz (slugft2) 72 53
Weights Group Calculations