01-25083. Proposed [Preliminary] Airworthiness Criteria for Airworthiness Certification of Transport Category Airships

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of availability; request for comments.

SUMMARY:

This notice announces the initiation of a Federal Aviation Administration (FAA) proposed airworthiness criteria for transport category airships. This notice advises the public, and especially manufacturers and potential manufacturers of transport category airships, that the FAA intends to develop an airworthiness criteria for transport category airships. This notice includes the Transport Airship Requirement (TAR) as developed by the Inspectie Verkeer en Waterstaat—Divisie Luchtvaart (CAA-NL), the civil aviation authority of the Netherlands, and the Luftfahrt Bundesamt (LBA), the civil aviation authority for Germany. The TAR is based on 14 CFR part 25 transport airplane requirements and FAA-P-8110-2 Airship Design Criteria. It is intended that the TAR will form the core of a United States airworthiness criteria for transport category airships. While considering the TAR as the core criteria for the certification of transport airships, the FAA may propose alternate or additional requirements for some portions of the TAR. This notice is necessary to advise the public of the development of this proposed airworthiness criteria and give all interested persons an opportunity to present their views on it.

DATE:

Send your comments by February 5, 2002.

Discussion: In September 2001, the Small Airplane Directorate proposed airworthiness criteria for transport category airships. We are making the proposed airworthiness criteria, including “Transport Airship Requirements” (TAR), dated March 2000, available to the public and to all manufacturers for their comments.

Airships are certificated under the provisions of 14 CFR 21.17(b), which allows the Administrator to designate appropriate airworthiness criteria for special classes of aircraft, including airships. The designated criteria should provide a level of safety equivalent to the airworthiness regulations contained in 14 CFR parts 23, 25, 27, 29, 31, 33 and 35. The FAA has decided that airworthiness criteria will be the most efficient and flexible method of obtaining an acceptable level of safety for transport category airships. The FAA bases this decision on the formative state of this industry and the potential for airships to develop into a new, viable, and important part of the aerospace industry. The FAA may decide to codify airship airworthiness requirements at a later time if warranted.

The criteria will be acceptable airworthiness criteria, but not the only acceptable criteria, for certificating a transport category airship in the United States. It is intended to utilize the TAR as a basis for a harmonized airworthiness standard (criteria) that will allow bilateral certification and validation of airships between nations that have adopted the TAR as a basis for the certification of such airships. This notice is intended to be the first step in developing a transport airship airworthiness criteria, public comments and subsequent FAA determinations may lead to modifications or additions to the proposed criteria as the body of knowledge concerning large airship manufacture and operations expands. It is anticipated that there will be modification of the criteria from the current noticed version as experience and research warrant such changes.

The proposed airworthiness criteria will apply to rigid, non-rigid, and semi-rigid transport category airships that are capable of vertical ascent (near equilibrium) operations. The proposed airworthiness criteria (and the TAR) does not include provisions for hybrid aircraft/airships that require or operate with significant dynamic lift. The FAA expects modifications and additions to the proposed criteria will be necessary for specific airship projects, due to the unique nature of each large airship design.

What is a transport airship? A transport airship is proposed to be defined as an airship that has an envelope volume larger than currently certificated normal category airships (425,000 cubic feet) or that has a combined crew-passenger capacity of 12 or more persons.

When adopted, the FAA is proposing that the airworthiness criteria for transport airships may be used for a fixed time period. The public notice of availability for the airworthiness criteria will specify the effective period of use to ensure periodic reviews of the criteria.

While considering the TAR as the core criteria for the certification of transport airships, the FAA has specific concerns and is interested in proposing alternate or additional requirements for some portions of the proposed criteria. The FAA especially desires to obtain public comment on the following:

Flight Tests. 14 CFR part 21, § 21.35, paragraphs (f)(1) and (f)(2), provides that a certain number of flight hours must be flown before type certification. In addition to the provisions of part 21, the FAA proposes that a transport category airship may be required to successfully accomplish a certain number of complete mooring, take off, and cargo exchange cycles prior to type certification. This may result in additional flight hours being required to accomplish this requirement, due to the longer mission times of airships.

Flight in Rough Air, Gust and Turbulence Loads. TAR paragraphs 261, 341 and other structural and handling requirements are based on knowledge of the turbulence and gust environments that the airship will encounter. The FAA is concerned that the determination of an appropriate gust model for analysis and the determination of the maximum gust and gust shape will be a limiting design parameter, especially for rigid and semi-rigid airships. Given the extremes of weather in the North American landmass (with respect to severity, magnitude and front speeds) and the historical experience concerning the loss of the Navy airships Shenandoah, Macon and Akron, the FAA desires to obtain additional specific comment on these requirements in the proposed criteria. The FAA anticipates that both structural and controllability issues will be relevant when considering gusts and turbulence and the typical operating environment of airships (less than 1500 feet AGL). There may well be a much greater reliance on operational limitations and interrelationship of operational and airworthiness requirements to obtain an acceptable level of safety with airship operations than has been the past practice with other aircraft.

Ditching and Emergency Evacuation. TAR paragraphs 801 and 803 address these concerns. However, additional specific analyses or tests will need to be proposed and performed to address these issues. Emergency evacuation or ditching of a large airship will entail problems that are not encountered with fixed wing aircraft. This could include collapse of the airship envelope, lifting, rolling or moving of the airship during evacuation, and hazardous effects of leaking lifting gas. Additionally, the possibility of removing or adding personnel onto the ship for medical or maintenance reasons during operations may need to be considered.

Environmental Issues. The proposed airworthiness requirement does not include provisions that may be required due to environmental laws. Environmental issues will be evaluated according to applicable regulations when an airship is actually certificated in the transport category.

Minimum Flight Crew, Relief Crew and Cargo Handling Crew. Large airships have not been operated in the United States for decades, the determination of crew duties and complements has never been determined by a United States civilian airworthiness authority. The FAA proposes a human factors study to be performed to establish acceptable workload, tasks, flight crew composition and duty rotation. This study will also include ground crew, cargo handling crew and related operations. This determination will also affect the flight deck and berth design.

Electrostatic Charging and Shock Hazards. The FAA proposes that additional provisions, similar to those proposed in the Joint Airworthiness Authorities (JAA) draft Joint Aviation Requirement (JAR) 25X899: Electrical Bonding and Protection Against Lightning and Static Electricity, be included to address electrostatic charging, shock hazards to crew and passengers, and electrical fault returns. For large airships that may use a great deal of non-conducting materials there is more concern with electrostatic charging and shock hazards.

Operational Rules. Operational requirements have not yet been proposed for the operation of large airships, therefore, the proposed airworthiness criteria may not thoroughly address these potential operational requirements. When such operational requirements are established, there could be additional certification or equipment requirements mandated for large airships to allow operation in the national airspace.

Design Standards for Changed Product and Continued Production. Transport airships have limited service experience worldwide and are anticipated to have extremely long service lives. Because of these factors, the FAA foresees a need to review and update the criteria on a regular basis. The FAA proposes limiting the useful life of the airworthiness criteria in order to ensure that this review cycle occurs. As a result, the FAA is proposing a different approach to the certification basis of transport airships and their modifications and would like comments on the following:

The FAA is proposing that a transport airship type design approval be of limited duration. At the end of this duration, aircraft in service could continue to be operated, but the airship could not be manufactured because the design approval would have lapsed. A new or revised type approval would be needed for a manufacturer to continue or resume production. The new or revised type approval would then be to the most current airworthiness criteria. This could mean that transport airships in continuing production may need to be updated to meet the most current (updated) airworthiness criteria. Using the most current airworthiness criteria would also apply to design approvals granted for the modification of transport airships.

When the criteria are updated, the revision effective date may need to define an effective date that includes a reasonable time for transport airship manufacturers and modifiers to comply with the updated criteria. Changes to the airworthiness criteria for transport airships would only be applied retroactively to previously manufactured airships if required by the changed criteria to address a safety of flight issue by issuance of an airworthiness directive.

ADDRESSES:

Copies of the proposed airworthiness criteria for transport category airships may be requested from the following: Small Airplane Directorate, Standards Office (ACE-110), Aircraft Certification Service, Federal Aviation Administration, 901 Locust Street, Room 301, Kansas City, MO 64106. The proposed airworthiness criteria will be available on the Internet within the next two weeks at the following address: http://www.faa.gov/​ programs_rsvp2/smart/ faa_home_page /certification/ aircraft/small_ airplane_directorate _news_proposed.html. Send all comments on the proposed airworthiness criteria for transport category airships to the individual identified under FOR FURTHER INFORMATION CONTACT.

FOR FURTHER INFORMATION CONTACT:

Mike Reyer or Karl Schletzbaum, Federal Aviation Administration, Small Airplane Directorate, Regulations & Policy, ACE-111, 901 Locust Street, Room 301, Kansas City, Missouri 64106; telephone: [phone] (M. Reyer); or [phone] (K. Schletzbaum); fax: [phone]; e-mail: [e-mail] or [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite your comments on the proposed airworthiness criteria for transport category airships. Send any data or views as you may desire. Identify the proposed transport category airship airworthiness criteria on your comments, and if you submit your comments in writing, send two copies of your comments to the above address. The Small Airplane Directorate will consider all communications received on or before the closing date for comments. We may change the proposal referred to in this notice because of the comments received.

You may also send comments to the following Internet address: [e-mail]. Comments sent by fax or the Internet must contain “Comments to proposed transport category airship airworthiness criteria” in the subject line. You do not need to send two copies if you fax your comments or send them through the Internet. If you send comments over the Internet as an attached electronic file, format it in either Microsoft Word 97 for Windows or ASCII text. State what specific change you are seeking to the proposed airworthiness criteria and include justification (for example, reasons or data) for each request.

Issued in Kansas City, Missouri on September 28, 2001.

Michael Gallagher,

Manager, Small Airplane Directorate, Aircraft Certification Service.