15 Oct 97
Army helicopters are routinely housed in hangars and similar facilities in order to perform
maintenance, make repairs, and provide protection from adverse weather. Because these aircraft
are usually fueled, they present a fire potential to the facility and the other valuable helicopters
and equipment also contained in it. In order to protect against a possible mishap, various fire
protection features and systems are essential. Sound fire protection engineering principles
mandate a protection system commensurate with the loss potential. Although the probability of a
catastrophic fire event may be low, the severity can be high. To mitigate the loss potential, this
ETL establishes requirements for cost-effective construction features and fire protection systems.
This ETL recognizes the difference in fire potential presented by helicopters as compared to
fixed-wing aircraft and provides an alternative to conventional foam fire protection systems.
This ETL has been prepared because there are currently no design criteria applicable to fire
protection for facilities housing helicopters. Currently-published criteria focus on the hazards and
fire potential associated with various sizes of fixed-wing aircraft. Attempts have been made by
designers to apply the provisions of NFPA 409, Aircraft Hangars, to facilities housing
helicopters. Unfortunately, NFPA 409 is applicable only to facilities housing fixed-wing aircraft,
not helicopters. Thus, in the absence of criteria specifically applicable to helicopter hangars,
various approaches to fire protection have been taken. This has resulted in a lack of uniformity of
protection features provided for Army helicopter hangars. This ETL specifically addresses the
hazards and loss potential posed by helicopters and provides criteria for fire protection features
and systems in new Army helicopter hangars as well as in retrofitting existing facilities.
3. GENERAL REQUIREMENTS
3.1 Construction Type. New hangar facilities will be of noncombustible construction (UBC
Type I or Type II) in accordance with MIL-HDBK-1008C.
3.2 Exit and Access Requirements. Means of egress from aircraft facilities will comply with
NFPA 101, Life Safety Code.
3.3 Distance from Other Buildings. Clear space around hangars will be provided to reduce fire
exposure between buildings and to assure access to such facilities from all sides. The
requirements for clear space separation outlined in NFPA 409, Chapter 2, will apply.