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
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
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
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
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
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
2.134
0.0
1.170
0.0
31.75
0.0
2.113
0.0
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
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
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
ATTACH RELEASE MECHANISM
Thermal Protection
When required, thermal protection systems
are provided for equipment
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
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