Section 3
Columbia 400 (LC41-550FG)
Emergency Procedures
Initial Issue of Manual: November 10, 2004
RC050002
Latest Revision Level/Date: -/11-10-2004
3-21
Best Glide Speed Versus Minimum Rate of Descent Speed
– The best distance glide speed
will provide the most distance covered over the ground for a given altitude loss, while the
minimum rate of descent speed, as its name suggests, will provide the least altitude lost in a
given time period. The best distance glide speed might be used in situations where a pilot, with
an engine failure but several thousand feet above the ground, is attempting to reach a distant
airport. The minimum rate of descent could be used in a situation when the pilot is over the
desired landing spot and wishes to maximize the time aloft for checklists and restart procedures.
Emergency Backup Boost Pump
– The backup boost pump is intended for use during an
emergency situation when failure of the engine driven pump has occurred. The switch that
controls this operation is on the rocker switch panel. The labeling on the switch reads BACKUP
PUMP ARMED. The switch is normally in the ARMED position for takeoff and climb to cruise
altitude and in the OFF position for cruise, descent, and approach to landing. The top of the
switch is engraved with the word OFF and is readable only when the switch is off.
If the engine driven pump malfunctions, ensure the backup boost pump is in the ARMED
position, and the backup fuel pump will turn on automatically when the fuel pressure is less than
about 5.5 psi. This condition will also activate a red FUEL light in the annunciator panel. When
the red FUEL light in the annunciator panel illuminates, there may be an audible degradation in
the smoothness of engine operation. With the backup pump operating, fuel is not as precisely
metered, compared to the normal engine driven system, and frequent mixture adjustments are
necessary when changes are made to the power settings. In particular, avoid large power
changes, since an over-rich or over-lean mixture will affect the proper operation of the engine.
With a failed engine driven pump, full power should be available, but power should be reduced
below 85% as soon as practical.
In the unlikely event of an engine driven fuel pump failure and a backup boost pump failure, the
primer switch may be held down to effectively restore fuel flow.
In general, as power is reduced from the 75% of BHP level, there must be a corresponding
leaning of the mixture. On an approach to landing, the normal checklist procedures must be
modified to exclude setting the mixture to full rich. It is best to make a partial power approach
with full flaps, and only reduce power when over the runway. If a balked landing is necessary,
coordinate the simultaneous application of mixture and throttle.
At power settings above the 85% level the problem is operating at too lean of a mixture. At full
throttle, the engine will produce approximately 100% of its rated BHP. In this situation, the fuel-
air mixture is lean of peak, and higher cylinder head temperatures and TIT readings will result
from extended use in the condition. Full throttle operations must be kept to a minimum and only
used to clear an obstacle, execute a balked landing, or other similar situations that require use of
all available power.
Critical Issues
(
Backup Boost Pump)
– One of the more critical times for an engine driven
boost pump failure is when the engine is at idle power, such as a descent for landing. There are
two reasons that make this situation more serious compared with other flight phases. (1) The
airplane is more likely to be at a lower altitude, which limits time for detection, analysis, and
corrective measures. (2) With the engine at idle power, there is no aural indication of engine