Installation Of Filter; Alternate Air Door; Fuel Injector Maintenance - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
8-55. SERVICE INSTRUCTIONS. Visually inspect the filter to determine its condition. Accumulation of
exhaust soot (fine carbon particles) collects on the filter and causes a rapid increase in restriction or short filter
life, washing is effective on carbon. soot and oil laden filters. Filters should be rejected for use if the paper filter
material is torn or ruptured or the housing is damaged. The filter gasket should have no tears and be securely
bonded in place. The usable life of the filter should be restricted to one year or 500 hours, whichever comes
first.
The method of cleaning the filter is as follows:
a. Tap the filter on a hard surface to remove any loose particles of dust, etc.
b. Wash the filter in a good non-sudsing detergent or the filter manufacturer's cleaner D-1400. Mix
two ounces of D-1400 to one gallon of water.
c. Soak the filter in solution for 15 minutes, then move the filter back and forth about two minutes
to free the dirt deposits from the filter.
d. Rinse the complete filter in a stream of water until rinse water is clear. (Maximum water pressure
40 psi.) A good thorough rinse is very important.
e. Dry filter thoroughly before reusing. Do not use light bulbs or extreme heat for drying.
f. After cleaning, hold filter up to a light bulb and inspect for damage or ruptures. Filters should
not be oiled.
8-56. INSTALLATION OF FILTER.
a. Position filter in filter plenum with gasket up.
b. Insert filter mounting brackets out through the slots in the plenum sides and secure with screws.
Tighten screws only enough to hold filter firm.
c. Install engine cowl. (Refer to paragraph 8-8.)
8-57. ALTERNATE AIR DOOR. The alternate air door is incorporated in the induction air tube between
the air filter and the turbocharger compressor inlet. The purpose of the door is to provide a source of air should
there be an air stoppage through the filter. The following should be checked during inspection:
a.
Door seal must fit flush with interior of duct opening.
b. Actuate the door to determine that it is not sticking or binding.
c. A minimum of a 9 pound force is required to open the door against the magnetic force. The 9
pound force is to be applied at the center of the door and perpendicular to the door surface, using a force
scale. Make several checks to insure 9 pound test is consistent. If the 9 pound force test fails, check to
insure both magnetic catch plates make full contact with alternate air door. Full contact can be obtained by
bending the magnetic catch bracket as needed.
d. Check the cockpit control cable for free travel.
e. Check that when the control knob in the cockpit is full in, the cable is adjusted to maintain .062
to .125 inch clearance between cam and alternate air door in the fully closed and magnetically latched
position.
8-58. FUEL INJECTOR.
8-59. FUEL INJECTOR MAINTENANCE.
a. In general, little attention is required between injector overhauls. However, it is recommended
that the following items be checked during periodic inspection of the engine:
1. Check tightness and lock of all nuts and screws which fasten the injector to the engine.
2. Check all fuel lines for tightness and evidence of leakage. A slight fuel stain adjacent to the
air bleed nozzles is not cause for concern.
3. Check throttle and mixture control rods and levers for tightness and lock.
4. Remove and clean the injector fuel inlet strainer at the first 25 hour inspection and each 50
hour inspection thereafter. Damaged strainer O-rings should be replaced.
Reissued: 9/23/80 POWER PLANT
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