Section 31.14

14 CFR Ch. I (1-1-19 Edition)

(b) Except as provided in Section 31.17(b), allowable weight tolerances during flight
testing are + 5 percent and Section10 percent.
[Amdt. 31-4, 45 FR 60179, Sept. 11, 1980]

Section 31.14 Weight limits.
(a) The range of weights over which
the balloon may be safely operated
must be established.
(b) Maximum weight. The maximum
weight is the highest weight at which
compliance with each applicable requirement of this part is shown. The
maximum weight must be established
so that it is not more than - 
(1) The highest weight selected by
the applicant;
(2) The design maximum weight
which is the highest weight at which
compliance with each applicable structural loading condition of this part is
shown; or
(3) The highest weight at which compliance with each applicable flight requirement of this part is shown.
(c) The information established under
paragraphs (a) and (b) of this section
must be made available to the pilot in
accordance with Section 31.81.

scent that can result from any single
failure of the heater assembly, fuel cell
system, gas value system, or maneuvering vent system, or from any single
tear in the balloon envelope between
tear stoppers:
(1) The maximum vertical velocity
attained.
(2) The altitude loss from the point of
failure to the point at which maximum
vertical velocity is attained.
(3) The altitude required to achieve
level flight after corrective action is
inititated, with the balloon descending
at the maximum vertical velocity determined in paragraph (a)(1) of this section.
(b) Procedures must be established
for landing at the maximum vertical
velocity determined in paragraph (a)(1)
of this section and for arresting that
descent rate in accordance with paragraph (a)(3) of this section.
[Amdt. 31-4, 45 FR 60179, Sept. 11, 1980]

Section 31.20 Controllability.
The applicant must show that the
balloon is safely controllable and maneuverable during takeoff, ascent, descent, and landing without requiring
exceptional piloting skill.

[Amdt. 31-3, 41 FR 55474, Dec. 20, 1976]
[Amdt. 31-3, 41 FR 55474, Dec. 20, 1976]

Section 31.16 Empty weight.
The empty weight must be determined by weighing the balloon with installed equipment but without lifting
gas or heater fuel.
[Amdt. 31-4, 45 FR 60179, Sept. 11, 1980]

Section 31.17 Performance: Climb.
(a) Each balloon must be capable of
climbing at least 300 feet in the first
minute after takeoff with a steady rate
of climb. Compliance with the requirements of this section must be shown at
each altitude and ambient temperature
for which approval is sought.
(b) Compliance with the requirements of paragraph (a) of this section
must be shown at the maximum weight
with a weight tolerance of + 5 percent.

spaschal on DSK3GDR082PROD with CFR

[Amdt. 31-4, 45 FR 60179, Sept. 11, 1980]

Section 31.19 Performance: Uncontrolled descent.
(a) The following must be determined
for the most critical uncontrolled de-

Subpart C - Strength Requirements
Section 31.21 Loads.
Strength requirements are specified
in terms of limit loads, that are the
maximum load to be expected in service, and ultimate loads, that are limit
loads multiplied by prescribed factors
of safety. Unless otherwise specified,
all prescribed loads are limit loads.
Section 31.23 Flight load factor.
In determining limit load, the limit
flight load factor must be at least 1.4.
Section 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

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