[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR31.47]

[Page 730-731]
 
                     TITLE 14--AERONAUTICS AND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 31--AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS--Table of Contents
 
                     Subpart D--Design Construction
 
Sec. 31.47  Burners.

    (a) If a burner is used to provide the lifting means, the system 
must be designed and installed so as not to create a fire hazard.
    (b) There must be shielding to protect parts adjacent to the burner 
flame, and the occupants, from heat effects.
    (c) There must be controls, instruments, or other equipment 
essential to the safe control and operation of the heater. They must be 
shown to be able to perform their intended functions during normal and 
emergency operation.
    (d) The burner system (including the burner unit, controls, fuel 
lines, fuel cells, regulators, control valves, and other related 
elements) must be substantiated by an endurance test of at least 40 
hours. Each element of the system must be installed and tested to 
simulate actual balloon installation and use.
    (1) The test program for the main blast valve operation of the 
burner must include:
    (i) Five hours at the maximum fuel pressure for which approval is 
sought, with a burn time for each one minute cycle of three to ten 
seconds. The burn time must be established so that each burner is 
subjected to the maximum thermal shock for temperature affected 
elements;
    (ii) Seven and one-half hours at an intermediate fuel pressure, with 
a burn time for each one minute cycle of three to ten seconds. An 
intermediate fuel pressure is 40 to 60 percent of the range between the 
maximum fuel pressure referenced in paragraph (d)(1)(i) of this section 
and minimum fuel pressure referenced in paragraph (d)(1)(iii);
    (iii) Six hours and fifteen minutes at the minimum fuel pressure for 
which approval is sought, with a burn time for each one minute cycle of 
three to ten seconds;
    (iv) Fifteen minutes of operation on vapor, with a burn time for 
each one minute cycle of at least 30 seconds; and
    (v) Fifteen hours of normal flight operation.
    (2) The test program for the secondary or backup operation of the 
burner must include six hours of operation with a burn time for each 
five minute cycle of one minute at an intermediate fuel pressure.
    (e) The test must also include at least three flameouts and 
restarts.

[[Page 731]]

    (f) Each element of the system must be serviceable at the end of the 
test.

[Doc. No. 1437, 29 FR 8258, July 1, 1964, as amended by Amdt. 31-2, 30 
FR 3377, Mar. 13, 1965; Amdt. 31-7, 61 FR 18223, Apr. 24, 1996; 61 FR 
20877, May 8, 1996]