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Airworthiness Certification - Where Are We?

Airworthiness Certification and subsequent regulation is concerned with preventing airplanes carrying passengers from falling out of the sky and the potential impact on people and things at the site of impact. It is helpful that UAVs carry no passengers however that fact does not mitigate the concerns regarding collateral damage.

All flight in the Unites States National Airspace System is regulated by the Federal Aviation Administration (FAA) under jurisdiction granted by law and the FAA regulates flight under the provision of Law codified within Code of Federal Regulations Title 14 - Aeronautics and Space.

Current FAA UAV policy is specified in AFS-400 UAS Policy 05-01, published on September 16, 2005.

The primary track to a UAV operations ticket is via the standard Airworthiness Certification Process. Airworthiness Certification specific to UAVs is found on the FAA's website. The FAA maintains an Airworthiness Certification Overview, and a complete Airworthiness Certification System for all airframes. UAVs are regulated under the Special Airworthiness Certificate, within the Experimental Category, and specifically  within the Special Airworthiness Certification for Unmanned Aircraft Systems. (click here to examine a Standard Airworthiness Application).

The Physical Sciences Laboratory in conjunction with and New Mexico State University is operating as an established UAS COE. PSL contracted to prepare the ERAST HALE UAS Certification Roadmap. This Roadmap is a must read having been constructed by Gary Nakagawa, formerly with the FAA's Certification branch (AIR). A short summary of the ERAST HALE Certification Roadmap that contains a comprehensive but brief concise explaination of levels of Airworthiness Certification from Registration through IACO Certification is provided. The Certification Certitude levels are listed below.

Level 1 Certitude - Registration Certificate

Level 2 Certitude - Experimental Certificate

Level 3 Certitude - Special Class Type Certificate

Level 4 Certitude - Production Under Type Certificate Only

Level 5 Certitude - Special Airworthiness Certificate

Level 6 Certitude - Standard Airworthiness Certificate

Level 7 Certitude - Air Operating Certificate

Level 8 Certitude - International Civil Aviation Organization Certificate

Certitude levels are a proxy for associated risk.


In September of 2005 the FAA has issued a fact sheet. In it, regarding Airworthiness certification the FAA states that " The first airworthiness certificates in the “Experimental” category (for research and development, crew training, or market survey) will be issued before the end of 2005." This has come to reality with the General Atomics Altai Experimental Airworthiness Certification in September 2005.


The scope of the variation in size and weight for UAVs, variable stall speeds as a result of airfoils, wing loading, and lift and aerodynamics variability makes for more difficulty in defining a regulatory reference frame and analytical paradigm.

Discussion:


Consider the UAVs depicted in the pictures above. UAVs range in size from 6" wingspans weighing less than a pound to airframes as large as small commercial jets. No one would argue the fact that large heavy airframes require airworthiness certification at least the equivalent of the regulations that govern passenger aircraft. What about small UAVs, with 6 - 10 ft wingspans, weighing in at 50 - 100 lbs, operating in controlled airspace. The Institution of Mechanical Engineers (UK) - Aerospace Engineering Division weighed in on the Airworthiness versus Size issue at their June 200 Conference. This PowerPoint presentation from the T-38 Committee of ASTM International discusses Airworthiness of Mini UAVs. The FAA has tasked the RTCA SC-203and the ASTM F-38 committees to evaluate airworthiness and develop standards and recommendations for UAV Airworthiness. This process is ongoing.

The FAA may conclude that it is not reasonable to demand that vendors of smaller UAVs meet the same requirements for airworthiness certification such as materials specifications and testing, manufacturing methods certification, maintenance schedules and so forth that are required for a Standard Airworthiness Certificate and governed by (FAA under Title 14 Code of Federal Regulations Part 21 and other regulations)? Such a regulatory ruling would adversely affect smaller airframe vendors and result in an industry shakeout before it even begins to gain traction. The ASTM F38 UAV Committee has posted this position paper and PowerPoint Presentation on Mini UAV Airworthiness (large download 1.5 Mb).

A study from MIT's International Center for Air Transportation (ICAT), by Weibel and Hansman entitled Safety Considerations for Operation of Different Classes of UAVs in the NAS, discusses safety concerns for different classes of UAVs. The report concludes "The results of the safety analysis indicate that it may be possible to operate small UAVs with few operational and size restrictions over the majority of the United States. As UAV mass increases, mitigation measures must be utilized to further reduce both ground impact and midair collision risks to target levels from FAA guidance. It is in the public interest to achieve the full benefits of UAV operations, while still preserving safety through effective mitigation of risks with the least possible restrictions. Therefore, a framework was presented under which several potential mitigation measures were introduced and could be evaluated. It is likely that UAVs will be significant users of the future NAS, and this report provides an analytical basis for evaluating future regulatory decisions."

The FAA is formulating policy anticipated in the form of AFS 400 UAS Policy 05-02, to be used by regulators to grant Civil or Commercial COA's for UAVs based on their “potential to do damage”. This guidance would rank UAVs into a classification system based upon weight, size, speed and formulate specific guidance’s base upon their capability to cause damage. Antecedents to his approach are found in the EASA's A-NPA and the OSD UAS NAS Integration Roadmap.

An alternative is regulation of flight by which airspace class the UAS is conducting operations ( e.g. - Class G airspace, under 1000 ft, within some variation of the anticipated, revision of Advisory Circular AC 91-57, which governs model aviation flight. ) AC 91-57 is a bare bones (and dated) advisory that relies heavily on the Academy of Model Aviation to set and enforce flight safety rules at local aerodromes. Currently large models, less than 100 lbs, are insurable by the AMA if flown at specific aerodromes, under 400 ft altitude, on a 72 MHz fequency spectrum and under local field safety officer supervision.

There is internal discussion within the FAA and the RTCA regarding which classification schema is the most valid. Some combination may emerge in new guidance at a time yet to be specified.

The final mix is to be determined and the FAA is guarded about projecting timing or specifics however G2 has it that new regulation policy could emerge as soon as March of 2006 or shortly there after. This date is clearly slipping right.

One clear need is for an organization of small UAV vendors to coalesce and start evaluating technologies and strategies to address the special issues related to SUAV flight at low altitude over fixed flight plans in public airspace. UAV MarketSpace is interested in working with SUAV vendors to organize an association to address this shortcoming in the dialogue.


In point of fact, inter-national UAV Airworthiness has not to date been established in the military community. NATO FINAS is meeting to make possible the creation of an international military UAV airworthiness code within a reasonable timeframe.


The UK's Civil Aviation Authority has issued its recommendations for Airworthiness Certification Standards for Civil UAVs.


The Canadian Military has weighed in on UAV Technical Airworthiness with this publication. South Africa gives this perspective on DENEL operations.

However the FAA has publicly committed for now to following the European lead and the Joint Aviation Authority and Eurocontrol, have assembled a UAV Task Force that has issued its final report. The report (PDF) recommends that UAVs should meet an equivalent level of safety compared with conventionally manned aircraft. The report stated that a civil (or military) certificate of airworthiness would be mandatory to operate in civil controlled airspace. It would bring in to effect a requirement for certified aircraft manufacturing facilities, aeronautical standards and materials for manufacture if adopted into regulations. UAVs would be subject to all aviation inspection processes and procedures. Only upon completion of a rigorous flight testing regimen would an airframe receive an airworthiness certification. This would probably apply to HALE and MALE UAVs. The newly released EASA's A-NPA contemplates a three class (A,B,C) system based upon weight and operating altitude.

 


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