Each fuel tank or each group of fuel tanks with interconnected vent systems must have an expansion space of not less than 2 percent of the tank capacity. It must be impossible to fill the fuel tank expansion space inadvertently with the rotorcraft in the normal ground attitude.
[Amdt. 27-23, 53 FR 34213, Sept. 2, 1988]
source: Docket No. 5074, 29 FR 15695, Nov. 24, 1964, unless otherwise noted.
cite as: 14 CFR 27.969