Model B-26, B-26A, B-26B Airplanes
July 31st, 1942
The instructions given on the following pages are those which have
been followed on previous occasions and may therefore be considered as
the best procedure available under the noted conditions. However,
unforeseen conditions may arise which have not previously been
experienced. It is therefore essential that each pilot and crew member
thoroughly familiarize himself with the airplane and its operating
systems in order to satisfactorily accomplish intended missions.
ELECTRICAL SYSTEM EMERGENCIES
A. In the event that a complete failure of the electrical system is
imminent; i.e., both generators have ceased to function and this fact
has not been noted in time to save the remaining energy in the
batteries; usually there will be an indication of the coming failure by
oscillation of the landing Gear and Flap indicator and/or oscillation of
the Autosyn Instruments:
1. Place Propeller Toggle Switches in FIXED PITCH.
2. IMMEDIATELY turn off both Generator Switches (This is important).
3. IMMEDIATELY turn off both Battery Switches.
NOTE: Even though Propeller Toggle Switch remains in AUTOMATIC,
propellers automatically fix when electrical current is cut, but place
Propeller Toggle Switch in FIXED PITCH position to prevent surge when
batteries are turned back on. Remember that any change in air speed
immediately changes the RPM. For instance, if cruising speed was 200 IAS,
RPM 2000, manifold pressure 25", and altitude 5000 feet at time
electrical current is lost, or you place propellers in fixed pitch, your
RPM will remain the same as long as you accurately hold your altitude
and Air Speed. If you allow nose to drop and your airspeed increases to
220 MPH you may get an increase of from 200 to 400 RPM. Conversely, if
you allow Airplane to climb, your RPM will immediately decrease. This
entirely normal reaction of Propellers in a fixed pitch condition,
sometimes in moments of stress, causes pilots to believe that Propellers
are "running away" or conversely "trying to feather". Naturally changes
in throttle settings will also affect your RPM; for you are now flying a
Fixed Pitch Propeller Type Airplane.
After 15 to 30 minutes flying, your batteries should rebuild
sufficient energy to allow you approximately five (5) minutes; (this is
an estimate only), to set your propellers to desired RPM by use of
INCREASE and/or DECREASE RPM Switches.
4. For landing purposes in FIXED PITCH, it has been found by
experimenting that a good optimum setting is approximately 2200 RPM,
with 25" manifold pressure at 150 MPH. This will give you plenty of
power if needed, to drag in the field or go around again.
B. The next condition of an electrical emergency to be considered is
the discovery that both Generators have failed but that the Batteries
are not completely discharged. In this condition, it is estimated from
the known capacities of the Batteries that you have at least thirty
minutes of full operation. In this case, if you are still several hours
from a landing, follow the same procedure:
1. Set Power and RPM to Desired Cruising.
2. Place Propeller Toggle Switches to FIXED PITCH.
3. Turn off both Generator Switches.
4. Turn off both Battery Switches.
Now, with a known reserve of electrical energy in batteries, it is
possible to turn on Battery Switches every ten or fifteen minutes, to
check Engine Instruments, etc., reserving sufficient energy to slake a
normal landing at destination with Propeller Toggle; Switches in
AUTOM1TIC. If any doubt of sufficient current when preparing to land,
follow procedure of setting propellers, etc. as outlined in (A-4) above.
On some take-offs, especially whore Throttles are "Jammed" ON too
suddenly to allowable rated power of 49", one or both engines may
over-rev momentarily causing a howling sound. This is entirely normal
and governors usually control the RPM back to 2600 or 2650 RPM. If,
however, as acceleration of airplane increases and the RPM goes above
the allowable without instantly coming back:
1. Cut throttles - discontinuing take-off.
NOTE: On most fields this can be done with absolutely no danger even
after reaching take-off speeds of from 100 to 110 MPH.
2. Check to see if Propeller Safety Switches are ON and if Propeller
Toggle Switches are in AUTOMATIC. If these are in proper settings -
governor failure is indicated.
3. Have Governor setting checked.
In many cases whore Propellers go to as high as 2700 to 2725 RPM on
take-off run, it is caused by Governor setting being a little high. An
experienced pilot generally has time enough during take-off run to see
if they hold at this RPM and also to try his Propeller Governor Controls
to see if they decrease the RPM, and hold it. In any case of doubt,
however, cut throttles and discontinue take-off.
If shortly after take-off a propeller Governor fails, allowing RPM
to increase rapidly, causing what is known erroneously as a "Run-Away"
Propeller, the seriousness of this emergency depends mainly on the Air
Speed, RPM and Power at time of Governor failure.
If for instance governor failed at 120 MPH with Landing Gear
retracting; or fully retracted with 48" HG Manifold Pressure and 2600
RPM, your Air Speed is naturally increasing, so RPM starts increasing
rapidly. If Air Speed is held at 120 MPH, RPM should remain nearly
constant at 2600. However, the natural inclination and in fact,
IMPERATIVE one is to obtain a safer airspeed, of at least 150 MPH. In
doing this, RPM will probably increase to 3000 RPM or more. We are
making this problem difficult by assuming that the DECREASE RPM Switch
and FEATHERING SWITCH are also Inoperative.
Naturally, if DECREASE RPM Switch is working, the correction is
relatively simple by allowing Air Speed to increase where desired and
holding RPM within safe limits by scans of the DECREASE RPM Switch.
Continuing our problem, however, from the point 120 MPH, 48" and
2600 RPM and the propeller starts "Running Away", the following
procedure will be accomplished very rapidly.
1. Leave good Engine alone but be prepared for YAW toward "Run Away"
2. Pull back Propeller Governor Control Handles, if RPM does not
3. Hold Propeller Toggle Switch to DECREASE RPM, and if RPM does not
4. Release Propeller Toggle Switch to FIXED PITCH POSITION.
5. Reduce Manifold Pressure on "Run Away" Engine to hold RPM at a
maximum of 3000.
6. WATCH FOR YAW - DON'T FORGET TO FLY AIRPLANE. Until safe Air
Speed and Altitude is reached, this is of more importance than anything
else! It may be necessary at this point to reduce power and RPM on good
Engine to keep Airplane under control. Use Trim Tabs to obtain best
flying conditions to hold 150 MPH in level flight. As you drop nose,
power must be reduced to keep from increasing Air Speed (which in turn
will cause; fixed Propeller to increase RPM). Keep Good Engine slightly
down and make all turns (gentle only) toward it. Return toward landing
It should be possible now by experimenting to find the best setting
for the "Run-Away" Engine. Reduce Manifold Pressure to reduce RPM as low
as possible, holding Air Speed constant but do not reduce Manifold
Pressure below 15" until ready to land. Use extreme caution in making
approach, being especially careful not to undershoot. Try to make your
landing a good 400' to 500' inside field, remembering that this airplane
can be brought to a stop in a very short distance.
From the above procedure it can be seen that a Propeller Governor
failure while at cruising speeds and altitudes is a relatively simple
problem, even should both Propeller Governors fail simultaneously.
By all laws of averages, this is an extremely remote possibility,
except in the case of a partial or complete electrical power failure,
which is not truly a governor failure but would cause propellers to fail
to respond to governors.
Propeller setting and Landing Procedure is fully covered under the
heading of ELECTRICAL SYSTEM EMERGENCIES.
These can be evidenced in several ways such as (1) failure of
landing gear to retract fully after take-off, (2) pressure gauge reading
below normal, or (3) pressure gauge reading "0".
CASE I. B-26, B-26A, B-26B Airplanes.
Hydraulic pressure normal before: take-off, but Landing Gear fails
to retract after take-off. This generally indicates an air lock around
Hydraulic humps, but may be a more serious condition, so if possible
follow this procedure:
1. Return Landing Gear Handle to "DOWN" position.
2. Pump Landing Gear down and locked with Hydraulic Hand Pump (on
Right Side of Pedestal)
3. Pump Flaps down as desired.
4. All White Handles to "NEUTRAL". (Important)
5. Check Landing Gear Indicator that Gear is down and locked.
6. Depress Brakes; pump up pressure to approximately 1200#. Release
and repeat several times.
7. Land, with Brakes slightly depressed (WARNING: Do not land with
brakes locked.) and co-pilot steadily pumping Hand Pump. Don not fully
release Brake Pedals at any time during glide and landing run, for this
will release the pressure being built up on them by the Hand Pump. With
this procedure, it should be possible to make a normal braking stop. If
not, use Emergency Air Brake Handle (on Center Stranger above and to the
right of Pilot's head).
8. Have Hydraulic System checked for malfunctioning.
If air is present in system, "Bleeding" can be accomplished from
cockpit by the following procedure on ground:
IMPORTANT: CHECK FOR PROPER RESERVOIR LEVEL AND ACCUMULATOR AIR
1. Both engines idling.
2. All White Handles to "NEUTRAL" - except Landing Gear, which is
3. Slowly push Emergency Nose Gear Handle (Red) to full "DOWN"
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