APPENDIX G – TASK, POST, PROCESS AND USE CONSIDERATIONS
Page G-1
UAS ROADMAP 2005
UAS ROADMAP 2005
APPENDIX H: RELIABILITY
OVERVIEW
The combined U.S. military UA fleet (Pioneers, Hunters, Predators, Global Hawks, and others) reached the 100,000 cumulative flight hour mark in 2002. Through 2004, this number has accelerated past 150,000 hours. This experience has provided quantifiable dividends in system reliability. Reliability is at the core of achieving routine airspace access, reducing acquisition system cost, and improving mission effectiveness for UA. Although it took the fleet of military UA 17 years to reach the 100,000 flight hour milestone, this appendix highlights the first comprehensive study1 to formally address the reliability issue for these increasingly utilized military assets. UA reliability is important because it underlies their
affordability, availability, and acceptance.
Affordability. The reliability of the DoD’s UA is closely tied to their affordability primarily because the Department has come to expect UA to be less expensive than their manned counterparts. This expectation is based on the UA’s generally smaller size (currently a savings of some $1,500 per pound) and the omission of those systems needed to support a pilot or aircrew, which can save 3,000 to 5,000 pounds in cockpit weight. Beyond these two measures, however, other cost saving measures to enhance affordability tend to impact reliability. System affordability has to be weighed against airworthiness and life-cycle costs (LCC). The demands of certification will tend to increase unit costs, perhaps beyond popular expectations. While attention needs to be directed at ways to increase reliability under cost constraints, additional up front investment has the prospect of lower LCC through reduced attrition from service-life extension and fewer mishap losses, in turn driving down requirements to acquire attrition reserves.
Availability. With the removal of the pilot, the rationale for including the level of redundancy, or for using man-rated components considered crucial for his safety, can go undefended in UA design reviews, and may be sacrificed for affordability. Less redundancy and lower quality components, while making UA even cheaper to produce, mean they become more prone to in-flight loss and more dependent on maintenance, impacting both their mission availability and ultimately their LCC.
Acceptance. Finally, improving reliability is key to winning the confidence of the general public, the acceptance of other aviation constituencies (airlines, general aviation, business aviation, etc.), and the willingness of the FAA to regulate UA flight. Regulation of UA is important because it will provide a legal basis for them to operate in the National Airspace System for the first time. This, in turn, should lead to their acceptance by international and foreign civil aviation authorities. Such acceptance will greatly facilitate obtaining overflight and landing privileges when larger, endurance UA deploy in support of contingencies. Regulation will also save time and resources within both the DoD and the FAA by providing one standardized, rapid process for granting flight clearances to replace today’s cumbersome, lengthy (up to 60 days) authorization process. A third benefit of regulation is that it could potentially lower production costs for the military market by encouraging the use of UA in civil and commercial applications. This overview presents reliability from several perspectives commonly used in reliability analysis.
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