Anthony P. (Tony) Taylor

Technical Director

Airborne Systems Inc

The System Approach to Spin Stall Parachute Recovery – An Update at 10+ Years

OutlineOutline

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 SSPRSA View of a SSPRS

Attach / ReleaseMechanism

Cockpit ControlPanel

Parachute / MortarSystem

Trailing Cone Cutter Aircraft wiring / componentsSupport Structure

What is A SSPRSWhat 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 RecoveryNext 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 VideoF-5E Flight Test Video

History of the System Approach at IrvinHistory 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 RequirementsThe 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)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 ResultThe 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 MortarParachute 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 DevicesVLJ 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 (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

Smaller/Lower Cost ARMSmaller/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 SystemControl 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

CONTROL PANEL

Fighter Class EnvironmentFighter 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 DesignLightning 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 InitiativesForward 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 TestControl 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

Additional EquipmentAdditional 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

MORTAR SYSTEM

ATTACH RELEASE MECHANISM

JSF Quadrapod StatusJSF 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 TestingGround 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 EquipmentCurrent 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 ProceduresManuals 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

WARNINGEXPLOSIVE POWEREDPARACHUTE MORTAR

CLEARP/N: 756415

STAY

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’

Lessons LearnedLessons 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 LearnedLessons LearnedThe Evolution Since the ‘First System ApproachThe 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 ChangesLessons 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)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 EquipmentLessons 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 LearnedOperational 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 RelatedOperational Incidents – Maintenance RelatedLearning LessonsLearning 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 SupportLessons 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 PlanningLessons 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 DeploymentGlobal Express In-Flight Deployment

T-50 Golden Eagle – Taxi Deployment TestT-50 Golden Eagle – Taxi Deployment Test

Courtesy KAI and ROKAF

T-50 Golden Eagle – In Flight DeploymentT-50 Golden Eagle – In Flight Deployment

Courtesy KAI and ROKAF

F-22 Raptor Taxi Test DeploymentF-22 Raptor Taxi Test Deployment

Courtesy Lockheed Martin