October 15, 1945 **PERFORMANCE** 04.708-04.725

04.08 GROUND AND WATER CHARACTERISTICS. Land planes shall be
maneuverable on the ground and shall be free from dangerous ground
looping tendencies and objectionable taxiing characteristics. The
seaworthiness and handling characteristics of seaplanes and amphibians
shall be demonstrated by tests deemed appropriate by the Administrator.
(See Sec. 04.452 for water stability requirements.)

1\. [Ground Characteristics]{.underline}

Taxiing tests should be conducted on smooth and rough ground as may
likely be encountered under normal operating conditions. Speeds should
be used which should vary up to approximately 70 percent of stalling
speed. Particular attention should be paid to the following:

Taxiing over rough ground.\--There is some evidence to indicate that
critical loads can be built up in taxiing over rough ground, even when
the shock-absorbing system is entirely satisfactory with respect to
capacity for landing purposes.

Brakes.\--Their adequacy in maneuvering on the ground and their tendency
to cause nosing-over should be investigated. Any bad tendency will
normally be exaggerated when taxiing in a strong side or tail wind.

2\. [Water Characteristics]{.underline}

In order to check water stability, taxiing tests should be made cross
wind in a fairly strong breeze.

Sailing ability should be investigated by actually sailing the aircraft
with appropriate use of the engine.

Porpoising tendencies should be investigated and reported upon for
extreme loading combinations.

Ability to maneuver up to and while on the step should be investigated
and reported on.

Effectiveness of the water rudders when provided should be checked.

3\. [Ski Handling.\--General]{.underline}

In the case of skis, the interpretation is that satisfactory landings
and take-offs are required, as well as satisfactory ski trim in normal
flight.

During landings, take-offs, taxiing, etc., particular attention should
be paid to the following:

a\. No undue directional instability.

b\. Satisfactory ability to make normal speed taxiing turns without
undue skidding tendency.

c\. No undue tendency to have the nose of each ski digging in during
landings or take-offs.

d\. Trimming gear adequate with no danger of damage occurring during
normal ground handling in taxiing or maneuvering over rough snow or
drifts.

e\. Ski trim in flight stable and satisfactory for all normal flight
attitudes including slips and skids.

f\. If braking devices are employed, attention should be given to
adequacy, effectiveness, and protection during normal operation on the
ground. Positive action should be required.

04,71 MODIFIED PERFORMANCE REQUIREMENTS FOR MULTIENGINE AIRPLANES NOT
CERTIFICATED IN THE TRANSPORT CATEGORY.

The weight of any multiengine airplane manufactured pursuant to a type
certificate issued prior to January 1, 1941, may be increased beyond the
values corresponding to the landing speed specified in Sec. 04.700 and
take-off requirements of Sec. 04.701, subject to the following
conditions:

\(A\) The increased weight shall be known as the provisional weight
(Sec. 04.103). The standard weight (Sec. 04.102) shall be the maximum
permissible weight for landing. The provisional weight shall be the
maximum permissible weight for take-off.

\(B\) Compliance with all the airworthiness requirements except landing
speed and take-off is required at the provisional weight, except that
the provisional weight may exceed the design weight on which the
structural loads for the landing conditions are based by an amount not
greater than 15 percent, provided that the airplane is shown to be
capable of safety withstanding the ground or water shock loads incident
to taking off at the provisional weight.

\(C\) The airplane shall be provided with suitable means for the rapid
and safe discharge of a quantity of fuel sufficient to reduce its weight
from the provisional weight to the standard weight.

\(D\) In no case shall the provisional weight exceed a value
corresponding to a landing speed of 5 miles per hour in excess of that
specified in Sec. 04.700, a take-off distance of 1,500 feet in the case
of landplanes, or a take-off time of 60 seconds in the case of
seaplanes; nor shall any provisional weight authorized in respect to any
type of airplane after January 1, 1945, exceed the value corresponding
to a rate of climb of at least 180 feet per minute at an altitude of
5,000 feet with the critical engine inoperative, its propeller
windmilling with the propeller control in a position which would allow
the engine (if operating normally and within approved limits) to develop
at least 50 percent of maximum except take-off engine speed, all other
engines operating at the take-off power available at such altitude, the
landing gear retracted, center of gravity in the most unfavorable
position permitted for take-off, and the flaps in the take-off position.

XXX

Corrections.\--In case it is considered necessary to use the weight or
other correction in obtaining the true rate of climb in these check
climbs, it will be acceptable to make these corrections as outlined in
Flight Engineering Report No. 3.

2\. [One Engine Inoperative Performance Tests]{.underline}

The primary purpose of the requirements of 04.723 is to obtain the
information necessary to inform the pilot of the one engine inoperative
performance of the airplane under any condition likely to be encountered
following an engine failure during the life of the airplane.

Unless some special reason is involved, \"such weights as are
necessary\" is to be the maximum weight for which certification is
sought. In order to accomplish this purpose it is necessary that
sawtooth climbs be conducted. The nature and number of these sawtooth
climbs should be the same as those described under 04.702 for the third
purpose involved, except that the critical engine as determined
immediately above is to be inoperative and the airplane is to be
otherwise in the condition most favorable to climb, i.e., flaps
retracted, inoperative propeller feathered or windmilling in high pitch.
Cowl flaps, if present, are to be in the position that is used to
demonstrate compliance with the cooling requirements as specified is
04.640.

In the past, the information which has been placed in the hands of the
pilot concerning the one engine inoperative performance has been limited
to a usable ceiling, i.e., the altitude in standard air at which the
best rate of climb is 50 feet per minute. In order to accomplish the
above purpose, however, it is obviously necessary to go beyond this and
it is requested that the applicant furnish a chart showing the one
engine inoperative best rate of climb and the corresponding true
indicated airspeed against altitude at various weights covering the
range of weight at which the airplane is likely to be operated.
Provision should be made for keeping the chart, once it is approved, in
the airplane at all times in a place conveniently accessible to the
pilot.

[Acceptable Method]{.underline}.\--Same as described under 04.702 except
additional data will need to be recorded.

Corrections.\--The corrections necessary to determine the actual rate of
climb are described in Flight Engineering Report No. 3.

04.724 AIRSPEED INDICATOR CALIBRATION. In accordance with Sec. 04.5800,
the airspeed indicator of the type airplane shall be calibrated in
flight. The method of calibration used shall be subject to the approval
of the Administrator.

04.725 CHECK OF FUEL SYSTEM. The operation of the fuel system shall be
checked in flight to determine its effectiveness under low fuel
condition and after changing from one supply tank to another. (See Sec.
04.620.) For such tests low fuel is defined as approximately 15
minutes\' supply in each tank tested at the maximum (except take-off)
power certified.

1\. [General]{.underline}

a\. The fuel system should be checked in flight to determine that it
will feed satisfactorily in climbs at the best angle of climb speed and
at the best gliding angle. Moderate rolls, slips and skids as might be
made accidentally in the above climbs and glides with low fuel should
not cause the engine(s) to cut out. The system should also feed promptly
after one tank has run dry and the other tank is turned on.

b\. Low fuel for the purpose of fuel system tests in flight is defined
as approximately (METO HP + 40) gallons in the tank tested. Each tank
will be tested unless the arrangement of the system indicates identical
results would be obtained. Special rulings will apply in cases of fuel
systems with several small tanks which would result in an unreasonably
large amount of residual fuel. If the fuel system has only one tank, the
engineering inspector may at his discretion during official tests
request the installation of a temporary auxiliary fuel tank for low fuel
flight tests in order to avoid the possibility of a forced landing due
to lack of fuel.

c\. Fuel systems of single engine aircraft shall not be considered
satisfactory if more than 10 seconds elapse after changing over from a
tank which has run dry in flight, before the engine resumes full power
operation.

d\. Systems with tank outlets and vents interconnected and so arranged
that it is impossible to feed from each tank individually should be
treated as single tank systems.

2\. [Acceptable Method]{.underline}

[Single or individual tank tests]{.underline}.\--(1) Flight tests should
be conducted with fuel arranged in the tanks so that each tank can be
tested separately with low fuel but always with a safe amount of fuel in
another tank. (2) If the aircraft has only one tank, the take-off will
be made with a safe amount of fuel and the tests conducted with [low
fuel]{.underline} as defined above. (3) The tests should be conducted by
changing over to the tank with low fuel after a safe altitude is
reached. Each position or attitude should be maintained for a period
sufficient to interrupt flow at the carburetor should the feed ports be
uncovered. (4) Tests should include steady climbs with maximum
permissible XXX