Optional lesson objective to address

1
Optional lesson objective - to address Reliabilit
y, Maintainability, Supportability, and Safety
Expectations - You will understand the issues
(benefits and penalties) associated with UAV
supportability and safety.
2
Why Consider Supportability?

• Operations Support and Safety are Key Cost
  Drivers for the Overall UAV System
• Operations Support (OS) Represent the Largest
  Percentage of the Life Cycle Cost (LCC)
• Reliability Maintainability Attributes of the
  Air Vehicle Drive Support Manpower
• - Affordability Issues Due to High Attrition
  Rates Constrain UAV Market Penetration (Military
  and Civilian)
• OS and Safety Issues Need to be Seriously
  Addressed During Pre-Concept Design
• It is Not Something That Can be Delayed
• You Get What You Pay For

3
Definitions

• Reliability
• The probability that an item can perform its
  intended function for a specified interval under
  stated conditions.
• Mean Time Between Failures (MTBF) (ususally in
  terms of flight hours)
• Failure Rate (failures per unit time)
• Probability (expressed as a decimal or
  percentage)
• Tasks and Responsibilities During Pre-Conceptual
  Design
• Allocations
• Predictions
• Functional Failure Modes Effects Analysis
• Design Reviews
• Trade Studies
• For purposes of this course, a discussion of
  the reliability issues and your proposed approach
  will suffice

4
Definitions

• Maintainability
• The measure of the ability of an item to be
  retained or restored to a specified condition
  when maintenance is performed by personnel having
  specified skill levels, using prescribed
  procedures and resources, at each prescribed
  level of maintenance and repair.
• Mean Time to Repair average of repair times
• Maintenance Manhours Per Flight Hour
• Crew Size Average number of individuals
  required to accomplish the maintenance action
• Tasks and Responsibilities During Pre-Conceptual
  Design
• Allocations
• Predictions
• Time Line Analyses (Combat Turns, etc.)
• Design Reviews
• Trade Studies
• For purposes of this course, a discussion of
  maintainability issues and your proposed approach
  will suffice

5
Definitions

• Supportability
• The degree to which system design characteristics
  and planned logistics resources, including
  manpower, meet system requirements.
• Direct Maintenance Manpower per Aircraft
• Logistics Footprint ( transport aircraft sorties
  to deploy squadrons support equipment, manpower
  and spares)
• Mission Capable Rate
• Not Mission Capable Supply (NMCS) Rate
• Tasks and Responsibilities During Pre-Conceptual
  Design
• Define Support (Maintenance Supply) Concept
• Estimate Manpower Sortie Generation Rates
• Define Deployment Concept Predict Logistics
  Footprint
• Trade Studies
• Requirements for this course underlined

6
Support Locations
Main Base
Forward Base
Emergency Base
7
Support Concept
8
What Kinds of RM Analyses Are Expected in
Pre-Conceptual Design?
Acquisition Life Cycle Phases
OTE
Concept Technology Development
System Development Demonstration
Operations Support
Production Deployment
RM Data Sources Techniques
Parametric Estimates
Supplier Predictions

• Weight
• Parts Count
• Surface Area
• Duty Cycle
• Sortie Length

Component Tests
Integration Tests

• Part Stress
• Environ Mod Sim
• Thermal Surveys
• FMEA/FMECA
• PHM Mod Sim
• Virtual Human MS

Flight Test

• Durability Tests
• Growth Tests
• Qual Tests

Field Data

• M Demos
• Surges
• Environmental Extremes
• Military Maintainers

• End Users Maintainers
• Production Configuration

RM Predictions Fidelity Increase with Design
Fidelity
9
What Is It About UAVs That Affects Supportability?

• Micro, Mini, or Larger?
• Proximity to Ground
• Interface with Loading Equipment
• Access to Daily Servicing Points
• Engine Removal
• Transportation / Deployment Considerations
• Hangar Space
• Refueling Times / Turnaround Times
• Storage vs. Flying
• Deployment Timelines
• Optempo
• Crew Sizes
• Weapons
• Self-Sufficiency
• Contractor Logistics Support Considerations
• Infrastructure

Size
CONOPS
Basing
10
What Is It About UAVs That Affects Supportability?
Endurance

• Airframe Life
• Inspection Criteria
• Consumables
• Redunancy / Mission Reliability
• Autonomous Refueling vs. Sizing for Range
• Deployment of Ground Stations
• LOS vs. BLOS Comms
• Mission Planning for Satellite Coverage
• Coordination with ATC
• Coordination with Ground Crews
• Design for Testability
• How Much Redundancy Can You Afford?
• How Much Safety Analysis Can You Afford?
• Approach to Support

Ground Segment
Cost / Fleet Size
11
Air Vehicle Eliminates Man-Rated Systems
Man-Rated Systems Are Eliminated

• Crew Station
• Instruments
• Cockpit Structure / Boarding Ladders
• Canopy
• Ejection Seat / Escape Provisions
• Throttle/Control Stick/Rudder Pedal
• Control Panels
• Crew Station Environmental Controls
• Heating/Cooling
• Pressurization
• Defog
• Oxygen System
• LOX or OBOGS
• Regulator
• Emergency/Survival Equipment

• OS Cost Reduction of 8 in Personnel Alone!
• No Egress Shop
• Eliminate Survival Skill
• Smaller, Less Costly ECS
• No LOX Consumables
• Less Support Equipment

12
Crew Station Benefits

• Equipment Moved Into Ground Control Station
• Flight Instruments / Information
• Displays
• Data Recording
• Reduced Environmental Qualification Testing
• No High g Testing Required
• Reduced Vibration Requirement (Maybe)
• No High Altitude Testing
• Increased Reliability
• Some Equipment 2-5 Times More Reliable
• Less Manpower Required for Maintenance
• Cheaper to Implement Redundancy

13
Weapons Loading / Engine Removal

• Proximity to Ground For Most UCAVs Complicates
  Weapons Loading
• Innovative Loading Schemes Can Mitigate
  Restricted Access
• Consider Hoists Alternate Lifting Devices
• X-45 Demo Uses Weapons Dolly and Ejectors Mounted
  on Weapon
• Robotic Loading May Help
• Considered By Navy for Ships
• Engine Removal Also Challenging
• Drop Down or Lift Out?
• Existing SE Sufficient?

14
Deployment and Transportation

• Storable UAVs Can Be Airlifted in Individual
  Storage Containers
• USAF UCAV Concept is to Deploy via C-17 (See Demo
  Below)
• Autonomous Aerial Refueling and/or Rearming May
  Allow Self-Ferry

15
Endurance Benefits

• Pilot Physical Limitations Limit Effective Sortie
  Length
• Endurance UAV Sortie Durations May Approach 48-60
  Hours!
• Ground Operators Can Work in Shifts
• UAVs Have Potential to Remain Aloft Indefinitely
• Requires Autonomous Refueling Technology
• 4 to 5 UCAVs Can Displace 24 Manned Fighters in
  24-Hour CAP
• Longer Sorties Mean Less Wear and Tear
• Cycle-Related Fatigue and Duty Cycles Reduced
• 80 of Fighter Failures are Constant on a
  Per-Sortie Basis
• Maintenance Manhours Per Flight Hour Reduction
• Knee in Curve at Approximately 24 Hour Sortie
  Length

This Study Assumed A Similar Level of
Maintainability
16
Long Endurance MeansFewer Sorties Per Flight Hour

• Assumes 80 of Failures are Constant on a Per
  Sortie Basis
• Manpower Eventually Reduces to a Constant to
  Retain a Minimum Number of Personnel of Each
  Specialty for All Shifts

MFTBM1 - Mean Flight Time Between Maintenance
(Inherent) MMH/FH - Maintenance Manhours Per
Flight Hour
This Study Assumed A Similar Level of
Maintainability
17
Endurance Benefits

• Pilot Physical Limitations Limit Effective Sortie
  Length
• Endurance UAV Sortie Durations May Approach 48-60
  Hours!
• Ground Operators Can Work in Shifts
• UAVs Have Potential to Remain Aloft Indefinitely
• Requires Autonomous Refueling Technology
• Longer Sorties Mean Less Wear and Tear
• Cycle-Related Fatigue and Duty Cycles Reduced
• 80 of Fighter Failures are Constant on a
  Per-Sortie Basis
• Maintenance Manhours Per Flight Hour Reduction
• Knee in Curve at Approximately 24 Hour Sortie
  Length

18
Ground Handling Options

• Preprogrammed Routes Using dGPS
• Accurate, Hands-Off
• Requires Site Survey, Detailed Mission Planning
• Likely Requires Deconflicted Ops with Other
  Aircraft
• Remote Control By Ground Crew
• Good Ground Situational Awareness
• Adds Complexity to Air Vehicle Design
• Remote Control By Ground Operator
• Good Ground Situational Awareness
• Minimal Impact on Manpower
• Hardware Intensive
• Needs On-Board Camera

19
Redundancy Considerations

• Redundancy Exists for 3 Reasons
• Safety
• Survivability
• Mission Reliability
• Consider Life Cycle Cost Sensitivities
• Maintenance Savings vs. Increased Loss of
  Aircraft
• Consider Mission Reliability Requirements
• For Flight Critical Systems (failure crash)
• Generally required to fail operational/fail safe
  (at a minimum)
• Triplex Redundancy is Most Cost-Effective on
  /Flight Hour Basis
• Extremely High Reliability (gt10,000 hrs MTBF) or
  Extremely Low Cost (lt1000/Channel) Are Required
  for Dual Redundancy to Be Cost Effective
• For Mission Critical Systems (mission fails or
  degraded)
• Generally required to fail operational (albeit
  degraded)
• Typically back-up most mission critical systems
  (radios, GPS, etc)

20
Redundancy Cost Trades
Module Cost/Channel 18,400 Average Repair
Cost 6000 Average Sortie Duration 4 .5
Hours UAV Unit Cost 10 Million Critical Failure
Rate 1/3 of MTBF
Trade Studies Will Determine Level of Redundancy
21
Training Concept

• Manned Aircraft Pilots Maintain Proficiency By
  Flying
• Require Minimum of 30 Flight Hours/Month
• Most Flight Hours In Lifetime are for Training
• UAV/UCAV Operator Interface Is Unique
• Actual vs. Simulated Flight Similar
• Keep UCAV In Storage Until War
• Reduced Spares/Consumables
• Reduced OS Costs
• Note this ConOps is changing
• as we speak

22
Next Subject

• Review of RMS Functions
• UAV UCAV RMS Considerations
• Supportability Attributes
• Subsystem Considerations
• Manpower
• OS Cost
• UAV Safety Lessons Learned

23
UAV and Drone Experience
Mishaps Per 100,000 Flight Hours Fighter
4.5 Manned QF-106 Drones 130 Unmanned QF-106
Drones 70 Pioneer UAV 167 Hunter
UAV 140 Predator UAV 27
Class A Cumulative Mishap Rate, 1997 Loss Rate
(non-combat)

• Primary Cause of Drone Mishaps is Old Age and
  Structural Integrity
• Primary Causes of UAV Mishaps
• Non-Aviation Qualified Parts (Pioneer Hunter)
• Inadequate Emergency Procedures Training / Lack
  of Concurrency
• Lack of Redundancy in Flight Critical Systems
• Inadequate Testing Configuration Control

24
Attrition Cost Comparison
Lower Unit Cost Does Not Necessarily Mean Lower
Life Cycle Cost! and theres a reason!
Losses Per 100K Flt. Hrs. 5.0 7.0 167 27
Cost Per Vehicle 25-50M 200K 1.0M 3.0M
Typical Fighter General Aviation Low Cost
UAV High Cost UAV
Global Hawk Goal is 10 per 100K Flight Hours
25
UAV Lessons Learned

• Carefully Weigh Risk When Considering Redundancy
• Establish Acceptable Mission Reliability Goals
• Trade Cost of Redundancy vs. Reduced Attrition
• Affordability is Usually Achieved at Higher Risk
• Recognize UAV/UCAV Mishap Rates Will Probably
  Exceed Manned
  Tactical Aircraft Mishap Rates
• As a Minimum, Consider Redundancy for
• Data Links
• Flight Controls
• Propulsion System Controls
• Utilize Mil-Spec or Commercial Aviation-Grade
  Parts
• Already Qualified for Operating Environment
  (Temperature, Altitude, Vibration, EMI, etc.)
• Better Reliability
• May Obviate Need for Expensive Qualification
  Testing
• Expensive for a Reason

26
UAV Lessons Learned

• Use Qualified Test Pilot During Testing
• Understands Aerodynamics Engineering
• First Responsibility is to Save Aircraft
• Trained to React to Unexpected Events
• Place Increased Emphasis on Operator-Vehicle
  Interface
• Provide Adequate Fault Annunciation to Operator
• Must Be Immediately Recognized
• Should Indicate Appropriate Operator Response
• Consider Operator Workload In Emergency
  Conditions
• Consider Operator Skill Level (Pilot, Novice,
  etc.)
• Segregate Houskeeping Maintenance Functions
  from Flight Ops Functions
• Train Emergency Procedures! (Especially for
  Flight Test)
• Adequately Test Hardware Prior to First Flight
• End-to-End Comms Loop (Including AV Antenna
  Multipath)
• Hardware-In-the-Loop Testing is Critical

27
UAV Lessons Learned

• Software Configuration Control
• Hazard Analysis Should Include Software Hazards
• A Software Change is a Configuration Change!
• Utilize Software-In-The-Loop Testing
• Automate Repetitive Functions to Alleviate
  Operator Fatigue and Improve Safety
• Plan Adequate Schedule for Software Test

28
How to Achieve Reliability

• Simplification Fewer parts means less things to
  fail
• Standardization Quality and tolerances all
  match
• Stress/Strength Derating Particularly for
  avionics
• Function Isolation Improved mission reliability
• Packaging Design Hermeticity, vibration
  isolation, etc.
• Redundancy Judicious use!
• Producibility and Tolerance Evaluation Quality
  issue
• Local Environment Evaluation Avoid hot spots
• Sensitivities Trade studies
• Drift and Degradation Design for it or test for
  it
• Development Test, test, test
• Reliability Design Checklists Lessons learned

29
Empirical Analysis of Reliability Trends
Historical Trend
10.0
7-9
5.0
3.0
EW 30Klb
EW 20Klb
MFHBF (Inherent )
1.0

• TREND Reliability Doubles Every 15 Years
• Newer Technologies
• Improved Manufacturing Processes (Quality)
• Increased Emphasis on Design for RMS

0.1
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
Year of Initial Production Delivery
30
UAV maintenance personnel
Parametric Data Shows Manpower Requirements are a
Function of Aircraft Speed, Weight (EW Wpay)
and Type

• UAV Comparison
• - Global Hawk fits overall manpower parametric
• - Predator falls well outside other aircraft
  norms
• Use this parametric to estimate maintenance
  manpower required for your design projects

Predator
Global Hawk
31
Intermission