Transcript Document

The System Approach to Spin Stall
Parachute Recovery – An Update at
10+ Years
Anthony P. (Tony) Taylor
Technical Director
Airborne Systems Inc
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!
A View of a SSPRS
Support Structure
Parachute / Mortar
System
Trailing Cone Cutter
Attach / Release
Mechanism
Aircraft wiring / components
Cockpit Control
Panel
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
Next Slide, a Video of an Actual Recovery
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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.
F-5E Flight Test Video
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
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
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!’
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
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 !
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
Attach/Release Mechanism (ARM)
ATTACH RELEASE MECHANISM
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Two designs exist that cover aircraft from
relatively light business jet through F-22/F35
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
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Full value of this approach is realized when
reviewed with the control technique (next
chart)
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
Control System
CONTROL PANEL
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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
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
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
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
CONTROL PANEL
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
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OPEN CIRCUIT - FSC1A (Deploy 1A)
 Reduces nuisance trips
Fail/4
FSC2A
ijs-off FSC1B
ijs-off FSC1A
ijs-off FSC2B
ijs-off

Pass
Pass
Pass
Pass
Fail
Pass
Pass
Pass
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2.134
0.0
1.170
0.0
31.75
0.0
2.113
0.0
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Fail/1
FTCA
FMLA
FSCR1A
FSCR2A
FSC1A
FSC2A
CALIBA
ij's-off
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Pass
Pass
Pass
Pass
Fail
Pass
Pass
Pas
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2.247
2.163
2.172
2.215
31.85
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274
2.18
4.768
0.0
Bit operates once per second, but
requires failure is present for three
straight occurrences before pilot report
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
Additional Equipment
MORTAR SYSTEM
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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
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Installation Structure
 Provide adaptive structure to mount
equipment and transfer parachute loads into
aircraft
 Analysis and test also provided
ATTACH RELEASE MECHANISM
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Thermal Protection
 When required, thermal protection systems
are provided for equipment
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Parachute and mortar
Deployed parachute riser
APU compartment and exhaust
Engine exhaust
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
Ground Support Equipment (GSE) and Integrated Testing
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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
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
Manuals and Procedures
WARNING:
!
BEFORE CONNECTING THE AIRCRAFT
WIRING TO THE MORTAR CARTRIDGE,
ESTABLISH A SAFETY ZONE AT THE
REAR OF THE AIRCRAFT.
 Seemingly a simple issue, well
developed manuals require
significant effort
 Installation Manual
 Includes initial and periodic
electrical tests – Functional Test
Procedure
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’
WARNING
EXPLOSIVE POWERED
PARACHUTE MORTAR
STAY
CLEAR
P/N: 756415
 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
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
Lessons Learned
The 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
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
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
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
 Pyro’s 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
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
Operational Incidents – Maintenance Related
Learning 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
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’
Lessons Learned – Flight Test Planning
 Consider the Planned Tests in the System design
 Balanced field length for taxi tests – What if parachute doesn’t 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
Global Express In-Flight Deployment
T-50 Golden Eagle – Taxi Deployment Test
Courtesy KAI and ROKAF
T-50 Golden Eagle – In Flight Deployment
Courtesy KAI and ROKAF
F-22 Raptor Taxi Test Deployment
Courtesy Lockheed Martin