this value at the rate of 3.6° F. per thousand feet of altitude above sea level until a temperature of -67° F. is reached above which altitude the temperature shall be constant at -67° F.

E (c) Correction factor for cylinder head, oil inlet, carburetor air, and engine and transmission coolant outlet temperatures. The cylinder head, oil inlet, carburetor air, and engine coolant outlet temperatures shall be corrected by adding the difference between the maximum anticipated air temperature and the temperature of the ambient air at the time of the first occurrence of maximum head, : oil, air, or coolant temperature recorded during the cooling test, unless a more rational correction is shown to be applicable.

(d) Correction factor for cylinder barrel temperatures. Cylinder barrel temperatures shall be corrected by adding 0.7 of the difference between the maximum anticipated air temperature and the temperature of the ambient air at the time of the first occurrence of the maximum cylinder barrel temperature recorded during the cooling test, unless a more rational correction is shown to be applicable.

§ 7.452 Climb cooling test procedure.

Climb cooling tests shall be conducted on all Category A rotorcraft in accordance with paragraphs (a) through (d) of this section. Such tests shall be conducted on all multiengine Category B rotorcraft that are certificated in accordance with the Transport Category A powerplant installation requirements as well as with § 7.384 (a) at the steady rate of climb or descent established in accord-ance with § 7.115 (b) (2).

(a) The climb or descent cooling test shall be conducted with the engine inoperative which produces the most adverse cooling conditions for the engine (s)

and powerplant components remaining in operation.

(b) All remaining engine (s) shall be operated at their maximum continuous power or at full throttle when above the critical altitude.

(c) After stabilizing temperatures in flight, the climb shall be started at or below the lower of the altitudes specified in subparagraphs (1) and (2) of this paragraph and shall be continued until at least 5 minutes after the occurrence of the highest temperature recorded, or until the maximum altitude is reached

For

for which certification is desired. Category B rotorcraft which do not have a positive rate of climb, the descent shall start at the all-engine-critical altitude and terminate at the higher of the altitudes specified in subparagraphs (3) and (4) of this paragraph:

(1) 1,000 feet below the engine critical altitude,

(2) 1,000 feet below the maximum altitude at which the rate of climb is equal to 150 fpm,

(3) The altitude at which level flight can be maintained with one engine operative, or

(4) Sea level.

(d) The climb or descent shall be conducted at an air speed selected to represent a normal operational practice for the configuration being tested. However, if it is determined that characteristics of the cooling provisions make them sensitive to rotorcraft speed, the most critical air speed shall be used, but need not exceed the speeds established in accordance with § 7.115 (a) (2) or (b) (2). It shall be acceptable to conduct the climb cooling test in conjunction with the takeoff cooling test of § 7.453.

§ 7.453 Category A; take-off cooling test procedure.

A take-off cooling test shall be conducted to demonstrate cooling during take-off and during subsequent climb with one engine inoperative. The following procedure shall be applicable:

(a) The take-off cooling test shall be commenced by stabilizing temperatures while hovering in ground effect with all engines operating at necessary power, with the appropriate cowl flap and shutter settings, and at the maximum weight for which certification is sought.

(b) After all temperatures have stabilized, the climb shall be started at the lowest practicable altitude and shall be conducted with one engine inoperative.

(c) The remaining engines shall be operated at take-off rpm and power (or at full throttle when above the take-off critical altitude) for the same time interval as take-off power is used during determination of the take-off flight path (see § 7.114 (a)).

(d) At the end of the time interval prescribed in paragraph (c) of this section the power shall be reduced to the maximum continuous power and the climb continued until at least 5 minutes

after the occurrence of the highest temperature recorded.

(e) The speeds shall be those used during determination of the take-off flight path (see § 7.114 (a)).

§ 7.454 Category B; cooling test procedure.

Cooling tests shall be conducted on all Category B rotorcraft in accordance with paragraphs (a) through (e) of this section (see § 7.452 for climb cooling tests where applicable).

(a) The cooling test shall be commenced by stabilizing temperatures while hovering in ground effect with necessary power and appropriate cowl flaps and shutter settings and at the maximum weight for which certification is sought.

(b) After all temperatures have stabilized, the climb shall be started at the lowest practicable altitude with take-off power.

(c) Take-off power shall be used for the same time interval as take-off power is used during determination of the takeoff flight path (see § 7.114 (b)).

(d) At the end of the time interval prescribed in paragraph (c) of this section the power shall be reduced to the maximum continuous power and the climb continued until at least 5 minutes after the occurrence of the highest temperature recorded.

(e) The cooling test shall be conducted at an air speed corresponding to normal operational practice for the configuration being tested. However, if it is determined that characteristics of the cooling provisions make them sensitive to rotorcraft speed, the most critical air speed shall be used, but need not exceed the best rate-of-climb speed with maximum continuous power.

§ 7.455 Hovering cooling test procedures.

Hovering cooling tests shall be conducted as follows:

(a) At maximum certificated weight or at the highest weight at which the rotorcraft is capable of hovering, if less than maximum certificated weight, at sea level using the power required to hover but not exceeding maximum continuous power, in the ground effect with still wind until at least 5 minutes after the occurrence of the highest temperature recorded.

(b) With all engines operating at maximum continuous power, the rotor

(a) The engine air induction system shall permit supplying the proper quantity of air to the engine under all conditions of operation.

(b) The induction system shall provide air for proper fuel metering and mixture distribution with the induction system valves in any position.

(c) Air intakes shall not open either within the engine accessory section or other areas of the powerplant compartment where emergence of backfire flame would constitute a fire hazard.

(d) Each engine shall be provided with an alternate air source.

(e) Alternate air intakes shall be so located as to preclude the entrance of rain, ice, or any other foreign matter. § 7.461 Induction system de-icing and anti-icing provisions.

(a) General. The engine air induction system shall incorporate means for the prevention and elimination of ice accumulations.

(b) Heat rise. Unless it is demonstrated that other means will accomplish the intent of paragraph (a) of this section, compliance with the following heat-rise provisions shall be demonstrated in air free of visible moisture at a temperature of 30° F.:

(1) Rotorcraft equipped with sea level engines employing conventional venturi carburetors shall have a preheater capable of providing a heat rise of 90° F. when the engines are operating at 60 percent of their maximum continuous power.

(2) Rotorcraft equipped with sea level engines employing carburetors which embody features tending to reduce the possibility of ice formation shall have a preheater capable of providing a heat rise of 70° F. when the engines are operating at 60 percent of their maximum continuous power.

(3) Rotorcraft equipped with altitude engines employing conventional venturi carburetors shall have a preheater capable of providing a heat rise of 120° F. when the engines are operating at 60 per

cent of their maximum continuous power.

(4) Rotorcraft equipped with altitude engines employing carburetors which embody features tending to reduce the possibility of ice formation shall have a preheater capable of providing a heat rise of 100° F. when the engines are operating at 60 percent of their maximum continuous power.

§ 7.462 Carburetor air preheater design. Carburetor air preheater shall incorporate the following provisions:

(a) Means shall be provided to assure ventilation of the preheater when the engine is being operated with cold air.

(b) The preheater shall be constructed to permit inspection of exhaust manifold parts which it surrounds and also to permit inspection of critical portions of the preheater itself.

§ 7.463 Induction system ducts.

Induction system ducts shall incorporate the following provisions:

(a) Induction system ducts ahead of the first stage of the supercharger shall be provided with drains to prevent hazardous accumulations of fuel and moisture in the ground attitude. The drains shall not discharge in locations which might cause a fire hazard.

(b) Sufficient strength shall be incorporated in the ducts to prevent induction system failures resulting from normal backfire conditions.

(c) Ducts which are connected to components of the rotorcraft between which relative motion could exist shall incorporate provisions for flexibility.

(d) Induction system ducts within any fire zone for which a fire-extinguishing system is required shall be of fire-resistant construction.

NOTE: Fireproof ducts are required in instances in which the duct may pass through a fire wall.

§ 7.464 Induction system screens.

If induction system screens are employed, they shall comply with the following provisions:

(a) Screens shall be located upstream from the carburetor.

(b) Screens shall not be located in portions of the induction system which constitute the only passage through which air can reach the engine, unless the screen is so located that it can be deiced by heated air.

§ 7.467

Exhaust system and installation components.

(a) General. (1) The exhaust system shall be constructed and arranged to assure the safe disposal of exhaust gases without the existence of a fire hazard or carbon monoxide contamination of air in personnel compartments.

(2) Unless appropriate precautions are taken, exhaust system parts shall not be located in hazardous proximity to portions of any system carrying flammable fluids or vapors nor shall they be located under portions of such systems where the latter could be subject to leakage.

(3) All rotorcraft components upon which hot exhaust gases might impinge, or which could be subjected to high temperatures due to proximity to exhaust system parts, shall be constructed of fireproof material. All exhaust system components shall be separated by means of fireproof shields from adjacent portions of the rotorcraft which are outside the engine compartment.

(4) Exhaust gases shall not discharge in a manner to cause a fire hazard with respect to any flammable fluid vent or drain.

(5) Exhaust gases shall not discharge at a location which will cause a glare seriously affecting pilot visibility at night.

(6) All exhaust system components shall be ventilated to prevent the existence of points of excessively high temperature.

(7) Exhaust shrouds shall be ventilated or insulated to avoid during normal operation a temperature sufficiently high to ignite any flammable fluids or vapors external to the shrouds.

(b) Exhaust piping. (1) Exhaust piping shall be constructed of material resistant to heat and corrosion, and shall incorporate provisions to prevent failure due to expansion when heated to operating temperatures.

(2) Exhaust pipes shall be supported to withstand all vibration and inertia loads to which they would be subjected in operation.

(3) Portions of the exhaust piping which are connected to components between which relative motion could exist shall incorporate provisions for flexibility.

(1)

(c) Exhaust heat exchangers. Exhaust heat exchangers shall be constructed and installed to assure their ability to withstand without failure all vibration, inertia, and other loads to which they would be subjected in operation.

(2) Exhaust heat exchangers shall be constructed of materials which are suitable for continued operation at high temperatures and which are resistant to corrosion due to elements contained in exhaust gases.

(3) Provision shall be made for the inspection of all critical portions of exhaust heat exchangers.

(4) Exhaust heat exchangers shall incorporate cooling provisions wherever they are subject to contact with exhaust gases.

(5) Exhaust heat exchangers or muffs shall incorporate no stagnant areas or liquid traps which would increase the possibility of ignition of flammable fluids or vapors which might be present in case of failure or malfunctioning of components carrying flammable fluids.

(d) Exhaust heating of ventilating air. If an exhaust heat exchanger is used for heating ventilating air used by personnel, a secondary heat exchanger shall be provided between the primary exhaust gas heat exchanger and the ventilating air system, unless it is demonstrated that other means used preclude harmful contamination of the ventilating air.

POWERPLANT CONTROLS AND ACCESSORIES

§ 7.470 Powerplant controls; general.

The provisions of § 7.353 shall be applicable to all powerplant controls with respect to location and arrangement, and the provisions of § 7.737 shall be applicable to all powerplant controls with respect to marking. All flexible powerplant controls shall be of an approved type. In addition, all powerplant controls shall comply with the following:

(a) Controls shall be so located that they cannot be inadvertently operated by personnel entering, leaving, or making normal movements in the cockpit.

(b) Controls shall maintain any set position without constant attention by flight personnel. They shall not creep due to control loads or vibration.

(c) Controls shall have strength and rigidity to withstand operating loads without failure and without excessive deflection.

(a) A separate throttle control shall be provided for each engine. Throttle controls shall be grouped and arranged to permit separate control of each engine and also simultaneous control of all engines in such a manner that proper synchronization of the power of all engines can be readily achieved.

(b) Throttle controls shall afford a positive and immediately responsive means of controlling the engines.

(c) If an antidetonant injection system is provided, the control shall be incorporated in the throttle controls, except that a separate control may be provided for the antidetonant injection pump.

§ 7.472 Ignition switches.

Ignition switches shall provide control for each ignition circuit on each engine. Means shall be provided for quickly shutting off all ignition by the grouping of switches or by providing a master ignition control. If a master ignition control is provided, a guard shall be incorporated to prevent inadvertent operation of the control.

§ 7.473 Mixture controls.

(a) If mixture controls are provided, a separate control shall be provided for each engine. The mixture controls shall

be grouped and arranged to permit separate control of each engine and also simultaneous control of all engines.

(b) Any intermediate position of the mixture controls which corresponds with a normal operating setting shall be provided with a means of identification by feel and by vision.

§ 7.474 Carburetor air preheat controls.

Separate carburetor air preheat controls shall be provided to regulate the temperature of the carburetor air for each engine.

§ 7.475 Supercharger controls.

Supercharger controls shall be accessible to the pilots, except where a separate flight engineer station with a control panel is provided, in which case they shall be accessible to the flight engineer.

§ 7.476 Rotor brake controls.

It shall be physically impossible to apply inadvertently the rotor brake in flight. A means shall be provided to warn the crew if the rotor brake has not been completely released prior to takeoff.

§ 7.477

Powerplant accessories.

(a) Engine mounted accessories shall be of a type approved for installation on the engine involved, and shall utilize the provisions made on the engine for mounting.

(b) Items of electrical equipment subject to arcing or sparking shall be installed in such a way as to minimize the possibility of their igniting flammable fluids or vapors which might be present.

(c) If continued rotation of an engine-driven cabin supercharger or any remote accessory driven by the engine will constitute a hazard in case malfunctioning occurs, means shall be provided to prevent hazardous rotation of such accessory without interfering with the continued operation of the engine. (See also § 7.358 (c).)

NOTE: Hazardous rotation may involve consideration of mechanical damage or sustained air flows which may be dangerous under certain conditions.

§ 7.478 Engine ignition systems.

(a) Battery ignition systems shall be supplemented with a generator which is automatically made available as an alternate source of electrical energy to permit continued engine operation in the event of the depletion of any battery.

(b) The capacity of batteries and generators shall be sufficient to meet the simultaneous demands of the engine ignition system and the greatest demands of any rotorcraft electrical system components which draw electrical energy from the same source.

(1) The design of the engine ignition system shall take into consideration the condition of an inoperative generator and the condition of a completely depleted battery when the generator is running at its normal operating speed.

(2) If only one battery is provided, the design of the engine ignition system shall take into consideration the condition in which the battery is completely depleted and the generator is operating at idling speed.

(3) Portions of magneto ground wires for separate ignition circuits which lie on the engine side of the fire wall shall be installed, located, or protected so as to minimize the possibility of simultaneous failure of two or more wires as a result of mechanical damage, electrical faults, etc.

(4) Ground wires for any engine shall not be routed through fire zones, except those associated with the engine which the wires serve, unless those portions of the wires which are located in such fire zones are fireproof or are protected against the possibility of damage by fire in a manner to render them fireproof. (See § 7.472 for ignition switches.)

(5) Ignition circuits shall be electrically independent of all other electrical circuits except circuits used for analyzing the operation of the ignition system.

(c) Means shall be provided to warn flight personnel if malfunctioning of any part of the electrical system is causing the continuous discharging of a battery which is necessary for engine ignition. (See § 7.472 for ignition switches.) POWERPLANT FIRE PROTECTION Designated fire zones.

§ 7.480

(a) Designated fire zones shall comprise the following regions: (See also § 7.385.)

(1) Engine power section,

(2) Engine accessory section,

(3) Complete powerplant compartments in which no isolation is provided between the engine power section and the engine accessory section,

(4) Auxiliary power unit compartments, and