Engine Fire Procedure 172K(XP)

Engine Fire Procedure 172K(XP)

<HTML>The Emergency Procedure for "Engine Fire on Starting for my 1980 172K Fuel injected (IO 360KB) reads like this:

The Cessna 172K manual

1. Aux Pump "Off"    2. Mixture "Idle cut off"  3. Parking Brake release
4. Fire ext obtain      5. Evacuate aircraft       6. Fire - Extinguish
(Note:This will be hard to do with the cowling buttoned up)

The Continental Maintenance & Operators manual:

1. Mixture - Idle cut off
2. Throttle - Full Open
3. Starter - Hold in cranking until fire extinguished
4. Evacuate if fire not quickly contained

I'd appreciate an comments on why I SHOULD NOT FOLLOW the Continental
manual -- other than the POH is suppose to be the last word.</HTML>

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Re: Engine Fire Procedure 172K(XP)

<HTML>I'd add for item #1, "DECLARE EMERGENCY".   Then follow the procedure (published or not) that is appropriate in your own judgement.  You may deviate from any procedure and any regulation to the extent necessary to meet the emergency.  The Continental procedure to continue cranking the engine is intended to "suck" the fire into the engine in order to 1) contain it and 2) extinguish it.  The mixture off at this point will actually be counterproductive, for as the engine starts, the fire would normally be sucked into the intake (IF it's an intake or overpriming condition fire) and the running engine would cause the propeller slipstream to blow the fire out.  Also, the thrust produced could be used to move the aircraft away from any puddled fuel on the ground.  A mixture at idle cutoff would prevent the engine from starting.  The idea of "mixture off" is intended to deprive the fire of fuel, and the mixture as a cause of overpriming is presumed to be a source of the fuel.  Keep in mind that an injected engine has induction drains that will drain excess fuel from the intake system onto the ground, and any fire present may migrate to the fuel puddles beneath the aircraft.  Taking the fire extinguisher with you may assist you in fighting the fire, but a safer precaution is a current and paid-up insurance policy.  Leave the fire-fighting to the professionals and get your pax and yourself safely away if the fire is not quickly contained by following the Continental procedure.
  (By the way,  I never use a parking brake.  The purpose of that item in the fire checklist is in order to enable the aircraft to be moved away from other aircraft, etc.  Many checklists list "set parking brake" or "set brake" as a pre-start item.  I personally only use the toe brakes, for several reasons.  1)Most light aircraft parking brakes only hold existing tension on braking systems.  Any slow loss of pressure will allow an aircraft to roll, which may go unnoticed to an operator who has mentally resigned himself to the idea that a "parking brake" has been set. 2)A brake system held by toe/foot pressure will continue to be pressurized by the operator even though it may have a slight "bleed-down" rate.  3) The operator is already properly positioned to apply additional braking if it should become necessary.  AND LAST BUT NOT LEAST 4) Single-engined Cessna parking brake systems are dangerous.  More than one airplane has blown a tire, ground-looped (even trycycle airplanes can do this), left the runway, etc. because a main wheel was inadvertently locked by the parking brake system prior to landing.  This can occur whenever a rudder is fully deflected (such as during a slip or as when landing in a cross-wind.)   The Cessna parking brake operates via a small lock on the master cylinder's operating shaft.  When the brake is applied and the parking brake "set", a small tabular lock is pulled up (and held by spring pressure) which cams the lock against the operating shaft.  This holds the brake cylinder in a "brakes-locked" position.  If prior to landing, the rudder is deflected far enough to contact the firewall pad Cessna uses for insulation on the aft face of the firewall, that tab can be deflected into the "brakes-locked" positon.  When landing, if the pilot has already applied brakes, ...or if during roll-out the pilot applies brakes, the tab will hold those brakes in the position that corresponds to the most used brake-pressure.  The pilot will not likely have time to assess the situation and manipulate the brakes to release.   (Remember that in order to release a parking brake that ADDITIONAL braking pressure must be first applied.  This will worsen the situation.)  This can result in an excursion off the runway, a ground loop, a blown tire, or all the above.  The parking brake system on my Cessna has been disabled and  removed.  I consider this a mandatory mod on taildraggers, and a highly desireable one on nose-draggers.</HTML>

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Re: Engine Fire Procedure 172K(XP)

<HTML>Thanks for your comment on Cessna's POH vs Continentials emergency fire on starting procedure. I think it's interesting that they differ so much.

I was not aware that the fuel injected engine had induction drains - thanks for that info.</HTML>

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