[Code of Federal Regulations]

[Title 14, Volume 1]

[Revised as of January 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 14CFR31.25]



[Page 761-762]

 

                     TITLE 14--AERONAUTICS AND SPACE

 

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

 

PART 31_AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS--Table of Contents

 

                     Subpart C_Strength Requirements

 

Sec. 31.25  Factor of safety.



    (a) Except as specified in paragraphs (b) and (c) of this section, 

the factor of safety is 1.5.

    (b) A factor of safety of at least five must be used in envelope 

design. A reduced factor of safety of at least two may be used if it is 

shown that the selected factor will preclude failure due to creep or 

instantaneous rupture from lack of rip stoppers. The selected factor 

must be applied to the more critical of the maximum operating pressure 

or envelope stress.



[[Page 762]]



    (c) A factor of safety of at least five must be used in the design 

of all fibrous or non-metallic parts of the rigging and related 

attachments of the envelope to basket, trapeze, or other means provided 

for carrying occupants. The primary attachments of the envelope to the 

basket, trapeze, or other means provided for carrying occupants must be 

designed so that failure is extremely remote or so that any single 

failure will not jeopardize safety of flight.

    (d) In applying factors of safety, the effect of temperature, and 

other operating characteristics, or both, that may affect strength of 

the balloon must be accounted for.

    (e) For design purposes, an occupant weight of at least 170 pounds 

must be assumed.



[Doc. No. 1437, 29 FR 8258, July 1, 1964, as amended by Amdt. 31-2, 30 

FR 3377, Mar. 13, 1965]