MIL-H-18325B(Aer)
QUALITY ASSURANCE PROVISIONS
4.
Classification - The inspection and testing of heating and ventilating
4.1
systems shall be considered as falling within the following classifications:
(a) Tests and Inspections to be conducted during trials.
(b) Tests and Inspections to be conducted during production.
4.2
Tests and Inspections to be Conducted during Trials. These tests
include all the test of this specification. The first airplane of each contract and the first
airplane in which any major change in the heating or ventilating system is incorporated
shall be flight tested as specified in Specification MIL-T-18606(Aer) to detemine conformance
with the requirements of this specification.
4.3
General Inspection.-The materials used in the construction of the heating
and/or ventilating system shall have been inspected at source of procurement by Navy
Inspectors in accordance with established procedures. The heating system shall be thoroughly
inspected and tested for conformance to the requirements of this specification with regard
to design, quality of construction, suitability of materials used, finish, markings, dimensions
and weight.
4.4 Carbon Monoxide and Leakage - Tests for carbon monoxide and leakage of
the heating and ventilating system shall be conducted in accordance with Section 3.
4.5
Noise Control - Measurements of the increase in SOUnd level in the
enclosed spaces caused by the operation of the heating or ventilating system shall be
conducted at the same time as the other sound Ievel measurements are conducted during the
trials and the results shall not exceed the values specified in paragraphs 3.12.1 and 3.12.2.
4.6
Ventilating Equipment -The airplane shall be operated under the flight
conditions specified in Section 3, the amount of ventilating air delivered at each outlet
shall be measured with all outlets open full and the amount of air delivered per occupant
determined by measurement with a calibrated orifice or venturimeter shall not be less than
the amount specified in Section 3. The controls shall then be adjusted to shut off the
system and a test of each outlet made to demonstrate that no appreciable leakage results.
Heating Equipment.
4.7
4.7.1
Temperature Limits - In addition to the tests necessary to determine
compliance with this specificaton the following additional temperatures shall be determined
while the airplane is in flight at minimum cruising speed at an altitude of 1000 feet and these
temperatures shall not exceed the following values. The temperature rise of the ventilating
air shall not exceed 275 degrees farenheit measured at a point 18 inches downstream of the
heater, the maximum temperature of the exterior of the heater and ducts witin reach of
operating personnel shall not exceed the value specified in Section 3, and the temperature of
the exhaust gases (combustion heater only) shall not exceed the value specified in Section 3.
4.7.2
Automatic Temperature Control - The hot air outlets shall then be .
partially blocked in such manner that the flow of air is reduced and the temperature
thereby increased at a rate of temperature change not in excess of 30 degrees Fahrenheit
per minute. If a Type I heater is installed, when the temperature of the ventilating
air reaches 350 degrees Fahrenheit plus or minus 10 degrees, the temperature control shall
operate either to reduce the temperature of the ventilating air or shut the heater off entirely.
If a Type II or Type III heating system iS installed, the light on the pilot's instrument
panel shall light or, if an automatically operating shut-off valve is installed, this valve shall
operate to shut off completely the flow of bested air.
Automatic Shutoff Controls -The heating system shall be allowed to
4.7.3
remain on while the airplane is landed and if a combustion heater without a blower is
installed, the heater shall cease operation when the ram air pressure falls below the required
minimum and the device for stopping the flow of fuel and turning off the igniter shall operate.
If a blower is incorporated in the combustion heating system, the device for starting the
blower shall operate when the ram pressure falls below the required minimum. If an exhaust type
heating system is installed, the temperature rise of the ventilating air delivered from the heat
interchanger shall not exceed 275 degrees Fahrenheit during taxiing or while the motors are
idling after landing.
4.7.4
Electrical Power Consumption.-If a Type I heating system is installed,
the electrical power consumption shall be determined for starting for continuous operation and
for the blower, if included in the system, and the consumption shal1 not exceed the values
specified in Specification MIL-H-5484.
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