Fuel System - Piper PA-46-350P Malibu Mirage Pilot's Manual And Operation Manual

PA-46-350P, MALIBU

7.17 FUEL SYSTEM

Fuel is stored in two main integral wing tanks (see Figure 7-27), located
outboard of the mid-wing splice. Fuel quantity held by each wing tank is 60
usable gallons with one gallon of unusable fuel, for a total of 122 gallons. The
minimum fuel grade is 100 or 100LL aviation grade. Each tank gravity feeds
fuel through finger screens into three lines leading to collector/sump tanks
located at the root of each wing, just aft of the main spar. During preflight the
collector/sump tank and one of the three lines can be inspected in each main
wheel well. Collector/sump tanks vent back to the main tanks by a fourth line
located forward of the main spar. The main tanks vent to the atmosphere by
non-icing vents installed in the most outboard forward access panels of each
wing tank. Reverse fuel flow from collector tanks to main tanks is prevented
by 2 flapper check valves installed in each collector tank. Collector tank
sumps are the lowest points in the fuel system, and each has a drain valve for
draining collector and main tanks.
Avoid prolonged uncoordinated flight to prevent uncovering
of fuel tank outlets and subsequent fuel starvation.
Each tank separately vents air in and fumes out to equalize pressure with
ambient conditions. This is accomplished through combination valves in non-
icing fuel tank vents located at the most outboard, forward tank access panels.
Do not insert objects into the wing vent as damage to
the combination valve could result in fuel leakage.
A plugged vent could result in fuel starvation. If a
restricted vent is suspected, select the opposite tank
immediately. Monitor the suspect wing and land as
soon as possible.
When opening the fuel tank filler cap, a rush of air will
normally be heard and felt. This is caused by the large
volume of vapor space in the wing tank, which is under
a slight pressure differential. This pressure is the
minimum required to open the combination valve in the
vent and does not represent a hazard.
ISSUED: FEBRUARY 23, 1999
WARNING
CAUTION
CAUTION
NOTE
SECTION 7
DESCR/OPERATION
REPORT: VB-1710
7-31