[Federal Register: May 8, 1998 (Volume 63, Number 89)] [Notices] [Page 25540-25541] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr08my98-105] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Proposed Change #3 to FAA-P-8110-2, Airship Design Criteria (ADC) AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of availability and request for comments. ----------------------------------------------------------------------- SUMMARY: Change 3 is based on a National Transportation Safety Board (NTSB) recommendation calling for envelope tear warning systems on new airship certification projects. The recommendation stems from an airship accident that resulted from an envelope failure. Change 3 requires that some means of indication or warning system will alert the pilot of envelope tears. This could be an elaborate warning system based on sensors or simple gauges located and marked such that an unusual indication would be obvious to the pilot. DATES: Comments must be received on or before June 8, 1998. ADDRESSES: Send all comments to: Federal Aviation Administration, Small Airplane Directorate, Standards Office, ACE-110, 601 East 12th Street, Kansas City, Missouri 64106. FOR FURTHER INFORMATION CONTACT: Lowell Foster, Regulations and Policy Branch, ACE-111, at the address above, telephone number (816) 426-6941. SUPPLEMENTARY INFORMATION: Any person may obtain a copy of this information by contacting the person named above under FOR FURTHER INFORMATION CONTACT. Comments Invited We invite interested parties to submit comments on the proposed change to the ADC. Commenters must identify the report number (FAA-P- 8110-2) and submit comments to the address specified above. The FAA will consider all communications received on or before the closing date for comments before issuing the final Change 3 to the ADC. The proposed changes to the ADC and comments received may be inspected at the Standards Office (ACE-110), 1201 Walnut, Suite 900, Kansas City, Missouri, between the hours of 7:30 a.m. and 4 p.m. weekdays, except Federal holidays. Background In 1993, an airship came to rest on top and draped over a seven- story building in New York, New York, after the airship deflated in flight and became uncontrollable. The airship suffered a large tear in the envelope, the material [[Page 25541]] that makes up the shape of the balloon portion of the airship. The NTSB subsequently investigated and recommended several changes to the FAA's airship design standards. One of the recommendations called for an envelope tear warning system. The primary reason for the NTSB's recommendation for the envelope tear warning system came from the crew's report. The pilot and passenger both stated that they were not aware of the loss of envelope pressure until the airship began to collapse, even though there was a pressure gauge and a low pressure indicator light to alert them of envelope damage. Although crew procedures for both major and minor envelope tears had been established, those actions were not accomplished because the crew did not initially recognize that the envelope was damaged. The emergency procedures for this airship, relating to a tear in the envelope, are to operate the airship with a very low pressure. Very low pressure causes the airship to lose rigidity, but minimizes the loss of helium while maintaining controllability. If the emergency procedure is not followed, ballonets will automatically attempt to keep the envelope pressure constant, forcing helium out through the tear. Ballonets are airbags contained within the envelope that are inflated with air to control the rigidity and sometimes the center of gravity (trim) of the airship. A warning light and alarm activate when the envelope pressure drops below a nominal level; however, if the ballonets continue to automatically inflate to maintain envelope pressure, the alarm system does not activate until substantial helium is lost. The NTSB noted that the airship was not equipped nor required to be equipped with a ballonet inflation rate transducer or other device, which might have alerted the crew to the loss of significant quantities of helium. The NTSB believes that had the airship been equipped with a better warning system, the pilot would have been alerted to the loss of pressure earlier and could have taken prudent emergency actions to improve the possibility of a controlled emergency landing. Issued in Kansas City, Missouri, on April 30, 1998. Michael Gallagher, Manager, Small Airplane Directorate, Aircraft Certification Service. Proposed Change #3 To FAA-P-8110-2 Airship Design Criteria (ADC) New Item: Add to 6.2 ``(i)'' Change 3 is based on a National Transportation Safety Board (NTSB) recommendation calling for envelope tear warning systems on new airship certification projects. The recommendation stems from an airship accident that resulted from an envelope failure. Change 3 requires that some means of indication or warning system will alert the pilot of envelope tears. The new paragraph will be added to item 6.2 as follows: (i) Means to warn the pilot of envelope tears. Acceptable compliance means include systems as simple as locating and marking both envelope and ballonet pressure gauges so that unusual indications (rapid loss of helium) are immediately noticeable to the pilot. If an airship valving system is complex or automatic, a system such as a ballonet airflow rate change sensor connected to a warning system may be more appropriate. [FR Doc. 98-12293 Filed 5-7-98; 8:45 am] BILLING CODE 4910-13-M