Anthony P. Tony Taylor

1
The System Approach to Spin Stall Parachute
Recovery An Update at 10 Years
Anthony P. (Tony) Taylor Technical
Director Airborne Systems Inc
2
Outline

• What is a Spin Stall Parachute Recovery System
  (SSPRS) ?
• History of the System Approach to SSPRS at Irvin
• The Challenge
• The Result - An Outline of a Basic SSPRS System
• Aircraft Installed Equipment
• Ground Support Equipment and Integrated Testing
• Well Developed Installation and Operation Manuals
• Interlaced Throughout Initiatives to Address
  the Requirements of the VLJ Market, and Recent
  Work on the Lightning II
• Lessons Learned
• The Evolution of Systems Since the First System
  Approach
• Examples of Operational Incidents, Major and
  Minor, Positive and Negative
• Major Events, safety related
• Minor Events, maintenance level but also safety
  related
• Some Operational Tests Your Personal Fam Flight!

3
A View of a SSPRS
4
What is A SSPRS

• Simply put, a parachute attached to the aircraft
  tail that lowers the AOA and thus restricts the
  Spin or Stall
• Great Example in next Video
• For Fairness, Other Approaches Exist
• Rockets Wing Tip or Tail Mounted
• Mass transfer Forward in some cases, Aft in
  other cases
• Deployable Fins at the Aircraft Tail
• While these have been studied and used
  occasionally, the Parachute method is the
  Aerospace industry standard
• One other significant note, many Business Jet Mfg
  also use another parachute for high speed drag
  augmentation.
• Mach Tuck and Deceleration out of Flutter points,
  as well as Attitude Control
• Similar approach as discussed herein however
  details of the situation can be significantly
  different

5
Next Slide, a Video of an Actual Recovery

• This is one of my favorite videos you will see
  why !
• Aircraft F-5E First Spin Test
• Location EAFB Ground to Air Video with Long
  Lens
• Pilot Dick Thomas
• Actually got to ask Dick about this test
• Summary Tried all the Adverse combinations
  (Stick and Rudder) and all the Proverse
  Combinations and all in between Finally, and
  Dick reported pretty late, went to the parachute.
  

6
F-5E Flight Test Video
7
History of the System Approach at Irvin

• Circa late 1995, Bombardier Flight Test Center
  (BFTC) invites Irvin to a meeting to review
  system requirements for the Global Express
  aircraft
• At that time, Irvin provides only the Parachute
  and Mortar
• Irvin is providing equipment for Canadair
  Aircraft only
• Lear Jet Aircraft are provided by another company
• BFTC has recently been created to Flight Test all
  Bombardier Aircraft
• Canadair has suffered in the past two (2)
  significant system failures
• CRJ Incident
• Challenger Incident
• Both caused loss of aircraft and some/all of
  flight crew
• The Challenge
• BFTC Challenges Irvin to become System Level
  provider of all the SSPRS Equipment
• Pete Reynolds outlines the basic system
  challenges
• BFTC and Irvin Engineers Define the Basic
  Requirements, and Recognize a Significant, but
  interesting Challenge

8
The Basic Requirements

• Original Requirements As Outlined with BFTC
• Dual Power Source
• Quad Electrical Circuits Where Possible
• Dual for Pyro Lock
• Reversible Parachute Lock
• Fast Acting Additional Parachute Lock
• Large Deploy Handle
• Rotate to Lock
• Pull to Deploy Parachute
• Fast Acting Lock Immediate
• Trailing Cone Cutter Immediate
• Parachute Deploy 0.5 Second Time Delay

9
The Basic Requirements (continued)

• Smaller Jettison Handle
• Covered by Deploy Handle
• Electrical Interlock
• Simple Lights
• Green Parachute Locked and Passing BIT
• White Parachute Unlocked All position Switches
  Agree
• Green Light Repeater on Glare Shield
• Built In Test
• Power
• Pyro Circuits
• Reversible Lock Switch Position
• Irvin Response at the meeting This is going to
  be hard, but it is going to be darn neat when it
  is finished!

10
The Result

• The result, both in the initial response and with
  years of maturation has been (what most consider)
  a marked improvement in the reliability, safety
  and testing of SSPRS systems
• Significant Results
• 1 Aircraft Recovery
• Several Aircraft Events which were Non-Events
• Tens of BIT detected faults which were real
  issues, resolved both before and during flight
• Several Service Related Incidents Including One
  Very Recent Which Result in Safety Notices and
  Procedure/Equipment Updates

11
Parachute and Mortar

• The Parachute and Mortar is the Irvin preferred
  installation
• Conical Ribbon (or other Ribbon) parachute is the
  preferred approach due to inherent strength and
  excellent stability
• Direct mortar deployment of the parachute
  provides the highest reliability approach
• High Energy
• Minimal part count
• Mortar also provides an efficient mounting
  container
• Relatively well weather protected
• Easily mounted to aircraft structure
• Images at the left provide examples of
• Initial Parachute Pack Deployment
• Fully Deployed Parachute
• Thanks to EAFB F-22 Raptor CTF !

12
VLJ Market Mortar vs. Other Devices

• Parachute Mortars have many positives
• Highly Reliable
• Energetic deployment
• Provide a Parachute Compartment
• And at least one negative
• Cost
• For one recent VLJ Customer Airborne has agreed
  to use Tractor Rocket Deployment Customer is
  very use to tractor rockets
• Airborne is pursuing a program to become more
  comfortable with the devices for the future

13
Attach/Release Mechanism (ARM)

• Two designs exist that cover aircraft from
  relatively light business jet through F-22/F-35
• Functional features are the same for all
  variants, these include
• Reversible lock through a servo motor
• Parachute retention through a low force shear pin
  that will release the parachute if not Locked
  to the aircraft
• Position switches for feedback of reversible lock
  position
• Pyro locking pin for fast acting (and redundant)
  lock when Recovery Parachute is deployed
• Redundant pyrotechnic cutters for parachute
  release
• These are much more reliable than any mechanical
  based release
• Full value of this approach is realized when
  reviewed with the control technique (next chart)

ATTACH RELEASE MECHANISM
14
Smaller/Lower Cost ARM

• Small Probably Lower Cost
• Current Low Force ARM is not that large, but
  price could be reduced
• IRAD Effort Planned for this year to work to
  reduce price and size

15
Control System

• Provides simple PVI that has eliminated all
  previously known errors
• Rotate Deploy Handle to Operate reversible,
  servo-motor lock
• Pull Deploy Handle begins Deployment sequence
• Irreversible Sequence
• Permanent Pyro-Lock fires to provide additional
  parachute lock
• Trailing Cone Cutter releases that device (if
  installed) Business Jet Issue
• Parachute deployment is delayed 0.5 seconds to
  allow above to complete
• Jettison Handle Not Active until Deployment
  Handled is pulled
• Jettison Handle is Electrically Interlocked

16
Fighter Class Environment

• Similar approach to previous however Large
  handles are not usually possible
• Replace with Buttons and switches
• Toggle for Lock/Unlock Function
• Mash Button for Deploy
• Guarded Toggle for Parachute Jettison
• Functionality remains largely the same
• One exception, T-50 program had room for Pull
  Handle configuration and preferred not to
  integrate the other approach.
• Integrated Pull Handles and controls into the
  mounting position for an MFD

17
Lightning II Design

• Same Electronics (Basically) Distributed Switch
  Design to Match Lightening II Cockpit environment
  and Pilot Desires
• The Latter Always Being a Risk
• Some Challenges in Switch Functionality and
  Environmental Testing are nearly behind us

18
Forward Lower Cost Initiatives

• Current Business and VLJ Class Aircraft use the
  Legacy Control Panel
• Specialized Switches, while very functional have
  become Very Expensive
• Internal BIT Processor has become obsolete over
  10 year old!
• Still available but only in limited special
  builds
• Internal Project to Upgrade and Update these
  issues
• May convert switch design to an Airborne Internal
  Design

19
Control System Built In Test

• Built In Test runs continuously and checks the
  following
• Current resistance of all pyrotechnic circuits
  a more precise test than simple continuity (as
  with test lights)
• Checks input power voltage
• Checks Sequence time delay and relays at power
  on only
• ARM position feedback switches
• Bit operates once per second, but requires
  failure is present for three straight occurrences
  before pilot report
• Reduces nuisance trips
• Flight Mode reports data to pilot via control
  panel lights and repeater
• Maintenance mode provides detailed results via
  laptop computer
• Allows quick isolation of problems

• OPEN CIRCUIT - FSC1A (Deploy 1A)
• Fail/4 FSC2A ijs-off FSC1B ijs-off FSC1A
  ijs-off FSC2B ijs-off
• Pass Pass Pass Pass Fail
  Pass Pass Pass
• 2.134 0.0 1.170 0.0 31.75
  0.0 2.113 0.0
•  
• 274
• Fail/1 FTCA FMLA FSCR1A FSCR2A FSC1A
  FSC2A CALIBA ij's-off
• Pass Pass Pass Pass Fail
  Pass Pass Pas
• 2.247 2.163 2.172 2.215 31.85
  2.18 4.768 0.0

20
Additional Equipment

• Aircraft Wiring
• Experience and requirements are provided for
  every customer
• TSP and termination locations are critical to EMI
  (read lightning) protection
• Some customers prefer Irvin provide aircraft
  wiring harnesses
• Installation Structure
• Provide adaptive structure to mount equipment and
  transfer parachute loads into aircraft
• Analysis and test also provided
• Thermal Protection
• When required, thermal protection systems are
  provided for equipment
• Parachute and mortar
• Deployed parachute riser
• APU compartment and exhaust
• Engine exhaust

21
JSF Quadrapod Status

• Working through Qualification of This Large
  Structure
• Some Lessons Learned Related to Vibration
  Qualification and Metal Plating
• Believe that these will be resolved shortly we
  are not holding up the program
• Will be well suited to help future customers

22
Ground Support Equipment (GSE) and Integrated
Testing

• Integrated testing provided through Sophisticated
  Break Out Box
• Allows failure insertion to assure BIT is
  functioning
• Provides Pyro Device Simulation Mode
• Allows Simulated functioning of Control System on
  aircraft
• Internal circuits limit current flow to
  milliseconds, as with real pyro devices
• Internal device measures current through each
  pyro path
• Allows review of delivered current and deployment
  sequence

23
Current Re-design With Modern Equipment

• Desire to Reduce Weight, Size and Cost
• Additional Customer Desire to Further Automate
  Testing Process
• Customer/Airborne collaboration to produce new
  device
• Another project slated for internal development
  this year
• Will also update device based on recent lesson
  learned during aircraft installation
• More on this later

24
Manuals and Procedures
 

• Seemingly a simple issue, well developed manuals
  require significant effort
• Installation Manual
• Includes initial and periodic electrical tests
  Functional Test Procedure
• Operation Manual pilot operations and emergency
  procedures
• De-Installation Manual
• Many systems have been damaged by mechanics
  assuming they know how to remove equipment
• Well developed Acceptance Test Procedures

WARNING
BEFORE CONNECTING THE AIRCRAFT WIRING TO THE
MORTAR CARTRIDGE, ESTABLISH A SAFETY ZONE AT THE
REAR OF THE AIRCRAFT.  
The switch settings must be as follows   Key
inserted in the Key lock Key lock in the
LOCKED position Deploy Switch Handle in the
UNLOCKED position Contact Breakers (BUS A
and BUS B) pulled
 
25
Lessons Learned

• System Approach to SSPRS
• This is critical to a successful high AOA program
• We continue to resist significant changes from
  what we believe is now proven
• The Value of the System Provider and The Ability
  to Learn the Lessons
• We were put into and remain in a unique position
  where we can learn from the problems of the past
• We continue to learn from these issues
• Need to form closer ties with Military customers,
  where big organizations and security serve to
  separate us from those lessons

26
Lessons LearnedThe Evolution Since the First
System Approach

• ARM Changes and Enhancements
• Servo Motor, Original Motor was too difficult to
  procure to support most programs
• Lock witness switches, original design had an
  issue with simultaneity of multiple arms in a
  single switch
• Fasteners, Original design incorporated
  commercial grade fasteners
• Parachute and Mortar
• Parachute Riser, customer interaction during
  entire program allows improved surveillance of
  installed equipment and enhanced designs for
  future installations
• UV, Thermal and Moisture Protection
• Load Limit Fitting, a Fuse link type device that
  some customers request to limit force that the
  parachute can apply to the aircraft
• After fielding one particular design, Irvin
  identified an unfavorable potential loading
  condition
• Units were recalled and modified to protect
  against that condition

27
Lessons Learned - Control Panel Changes

• Original Jettison Switch was not Spring Return
• Identified as a design discrepancy and corrected
• Original Units Retrofitted
• Original Design required one fault to complete
  pilot declaration BIT fault light is latched
• Experience has shown that ground plane voltage
  fluctuations can provide occasional fault
• Algorithm changed to require three faults in a
  row before annunciation
• Significantly improved performance

28
Lessons Learned Control Panel Changes
(continued)

• BFTC identified (post Global Express), that
  single internal switch failure (fails closed)
  could lock and deploy parachute
• Circuit modified such that two switch closures
  are required to complete deploy command
• Retains most of quad-redundant architecture
  ability to deploy parachute
• Currently incorporated in all fielded systems
• Aircraft Wiring, Original installations did not
  require wire twisting, shielding or specific
  termination location
• Result of lighting event described later
• Lessons learned now incorporated and recommended
  to all customers

29
Lessons Learned Ground Test Equipment

• Original design used automotive class (Buss)
  fuses as pyro simulator
• We were frequent guests at Radio Shack or Auto
  Parts stores
• Choice between testing with fuse of lower
  current, or risking warm aircraft wire
• Pyros require 4 amps for 10 msec to fire
• A 4 amp fuse will take 4 amps for minutes to
  hours
• Developed current pyro simulator device, with
  current trace recording far superior monitoring
  
• Currently working on Fool Proof system which
  will prevent
• accidental firing from improper connection

30
Operational Incidents Lessons Learned

• Global Express, Successful Recovery
• Locked in deep stall
• Yoke full forward for 10-20 seconds, no result
• Deploy parachute, recovery within seconds
• Aware of some other events at commercial
  (business jet) customers, details to sketchy for
  discussion, however, recoveries have been
  completed high and low speed
• F-16, flies Spin Systems even today
• Edwards
• Worldwide, we continue to provide new systems
• Has had operational incidents such as damaged
  connectors, program continues to take appropriate
  corrective actions

31
Operational Incidents Maintenance
RelatedLearning Lessons

• Have detected many real world failures
• Bad power, Open breakers, etc
• Poor ground connections in flight
• Was a serious issue as this related to all pyros
  in the system essentially the ground system was
  a single point failure
• Connectors not properly connected
• Bent connector pins
• More than one occurrence
• Ask my about my incident if we have time for
  questions !
• Still suffer occasional hanger firing event
• Never with Irvin personnel present
• No injuries or significant equipment damage to
  date
• Of course the spin system needs some work
• Always traced to not following procedures
• Working on a fool proof system without
  disturbing excellent reliability of the flight
  system

32
Lessons Learned Recent Support

• Incident With Recent Pyro Vendor
• Devices were NOT Meeting Performance
  Specification
• Discovered During NASA Program Testing
• Failure Analysis Provides Sufficient Doubt about
  Reliability of Fielded Devices
• Airborne Decides to Recall and Replace Fielded
  Devices
• Hangar Deployment Event During Our Installation
• Root Cause Traced to Lack of Ground in AC Supply
• Safety Advisory Issued to All Customers of this
  Equipment
• Future Designs Will Eliminate this Design
  Feature

33
Lessons Learned Flight Test Planning

• Consider the Planned Tests in the System design
• Balanced field length for taxi tests What if
  parachute doesnt deploy, do we have runway to
  stop ?
• In-flight deployment, is this parachute force
  higher than emergency recovery ?
• Image below is C-17 with reefed parachute to
  address that issue

34
Global Express In-Flight Deployment
35
T-50 Golden Eagle Taxi Deployment Test
Courtesy KAI and ROKAF
36
T-50 Golden Eagle In Flight Deployment
Courtesy KAI and ROKAF
37
F-22 Raptor Taxi Test Deployment
Courtesy Lockheed Martin