1、k 1 MIL-T-LB606 16 m 3999906 0425769 2 m . r- - _ MILITARY SPECIFICATION TEST PROCEDURES FOR AIRCRAFT CABIN PRESSURIZING AND AIR CONDITIONING SYSTEMS This specification has been approved by the Bureau of Aeronautics, Department of the Navy 1. SCOPE 1.1 This specification covers the testing of cabin
2、pressurizing and air conditioning systems as installed in aircraft to demonstrate safety and satisfactory performance of the installation. The procedures outlined herein shall be followed, as applicable, for the testing of pressurized and non-pressurized aircraft. 2. APPLICABLE DOCUMENTS 2.1 The fol
3、lowing specifications and publications, of the Issue in effect on date of invitation for bids, form a part of this specification. SPECIFICATIONS MILITARY MIL-T-5842A Transparent Areas, Anti-Icing, Defrosting and Defogging Systems, General Specification for PUBLICATIONS AIR FORCX - NAVY AERONAUTICAL
4、BLIXTIN No. 421 Atmospheric Proprieties - Extreme Cold and Hot; Standard for Aeronautical Design (When requesting specifications, standards, drawings, and publications refer 60 both title and number. Copies of this specification and applicable specifications may be obtained upon application to the C
5、ommanding Officer, U. S. Naval Air Station, Johnsville, Pennsylvania, Attention Technical Records Division) 3. REQUIREMENTS 3.1 3.1.1 Suitable Instrumentation shall be installed to determine the weight flow of air, the temperature differential, and the pressure drop through each of the major compone
6、nts of the system. The accuracy of these measurements should be within plus OE minus 5 percent. 3.1.2 cent of passenger and crew accommodations occupied during cooling tests and a maximum of 10 percent of the passenger accommodations occupied during heating tests. tribction from forward to rear and
7、top to bottom of all occupied spaces within the air- plane. 3.1.4 Equipment shall be provided to determine the direction of flow and the General test equipment and requirements. System performance tests shall be conducted with a minimum of 75 per- 3*1.3 Instrumentation shall be provided to determine
8、 the temperature dis- Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_-_. _- _.I- _I_p- MIL-T-1bOb 16 W 7799906 0425770 7 W - aircraft at regular intervals using a reliable type of psychrometer. Pressure taps shall be so located as to determine all
9、pressures 3.3.5 Air velocity measurements. 3.3.5.1 A suitable velometer shall be used to determine air velocities in 3.3.5.2 Air velocities across the cabin thermostat sensing element and passenger and crew compartments. temperature indicating instrument, if installed, shall be determined by use of
10、a suit- able velometer. 3.3.6 in order that rates of temperature and pressure changes and time intervals required to obtain stab?lized conditions within the cabin can be noted. Time measurements.-Time measurements shall be recorded continuously 4. QUALITY ASSURANCE PROVISIONS . 4.1 Ground tests. 4.1
11、.1 Safety tests.-The aircraft shall be inspected to determine that all cabin air entries are so located that no drain or exhaust of inflammable or noxious fluid and gases can enter the scoop during flight or on the ground during cross wind conditions. . 4.1.1.1 Combustion heater installations. 4.1.1
12、.1.1 With an adjustable external power source connected to the airplane, the voltage shall be adjusted to that normally supplied by the aircraft system. 4.1.1.1.2 If the installation does not include blowers required for ground operation, external equipment required to supply in-flight conditions sh
13、all be attached. 4,1.1.1.3 With blowers in operation, the aircraft heating system shall be turned on and checked for normal operation. 4.1.1.1.4 With system operating normally, the combustion air source shail be disconnected or deactivated, to determine that no unsafe condition will be created by lo
14、ss of combustion air through failure of combustion air blower or icing of combustion air scoop in flight, System shall be adjusted as required, 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-18606( Aer ) 4.1.1.1.5 with system operating norma
15、lly, the ventilating air source shall be disconnected or deactivated to determine that no unsafe condition will be created by loss of ventilating air through failure of equipment or icing of air inlet in flight 4.1.1.1.6 With system operating normally, deactivate or bypass the normal temperature con
16、trol system to allow heater outlet air temperature to increase to the overheat switch setting. (Reduce ventilating air flow if required.) determined that no unsafe Condition exists at the temperatures encountered and that the overheat circuit functions properly. supplied to the aircraft until all of
17、 the components of the system cease to operate. It shall be determined that no unsafe condition is created due to low voltage operation. With the system turned on and all electrical power disconnected from the aircraft (external blowers operating if used), reduce the voltage to 50 per- cent of the n
18、ormal aircraft system voltage and reGonnect to the aircraft. Gradually increase the voltage until all components are operating normally and it shall be determined that no unsafe condition is created by low voltage condition. It shall be 4.1.1.1.7 With the system operating normally, gradually decreas
19、e the voltage 4.1.1.1.8 4.1.1.1.9 Conditions required to cause the aircraft heater to backfire shall be created to determine that combustion air and exhaust systems are secure and adequate for the heater. These conditions may be created by reduction of combustion air flow o? disconnecting the igniti
20、on system for a brief period of time. At least three substantial backfires shall be created before considering the system adequate. Ducts and heater shall be inspected for damage after test. lations shall be tested to show that no unsafe condition would be created by failure of the exhaust gas passa
21、ge within the unit. that pressures within the ventilating air passage are sufficient to prevent flow of exhaust gases into this passage. 4.1.1.2 Exhaust gas heat exchangers.-Engine exhaust gas heat exchanger instal- One means of verification would be to ascertain 4.1.2 Performance tests. 4.1.2.1 Gro
22、und tests ahall be conducted on aircraft equipped with ground conditioning equipment to determine if satisfactory temperatures and air flow rates are obtained. The air distribution shall be observed and flow rates measured to determine proper balance of the s stem. All temperatures, pressures, air v
23、elocities, and humidity (in transports7 specified in section 3 shall be recorded. -4.1.2.2 On pressurized aircraft, ground operation shall be tested or other- wise analyzed in order to determine the optimum configuration for comfort in hot weather while the airplane is taxiing or waiting take-off cl
24、earance. determine the cabin leakage rate. Pressure controls, flow controls and all pressure relief valves shall be checked to ascertain that the units are operating properly and are within tolerance limits. 4.1.2.3 Pressurized aircraft shall be pressurized to design differential to 4.2.1- Safety te
25、sts. 4.2.1.1 Smoke removal procedures shall be satisfactorily demonstrated. Protect all crew members and observers with suitable protective masks and discharge or manufacture sufficient smoke to fill the cabin. effected and the time required to remove smoke from crew and passenger compartments recor
26、ded. stearate and Freon-12. be demonstrated that no gases enter the air conditioning system during this operation. For pressurized aircraft, this test shall be conducted first with the cabin pressuriz- Smoke removal procedures shall be Smoke may be simulated by using an aerosol type container charge
27、d with butyl 4.2.1.2 The fuel tank dumping procedure shall be carried out, ,and it shall 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-LbOb Lb 777770b O425773 4 1-T-18606( Aer) ing system in normal operation, and secondly with the auxiliary
28、 ram air system in use. 4.2.1.3 The time required i;o dump cabin pressure shall be determined at several altitudes. Data showing the rate of pressure decay after actuation of the cabin safety valve shall be presented for each altitude investigated. These tests shall be conducted with maximum airflow
29、 entering the cabin from the conditioning system. excess positive and negative pressures within the cabin shall be thoroughly investi- gated + the taperature control and air flow control system components shall cause no hazard to the crew or passengers or affect safety of flight. 4.2.1.6 satisfactor
30、ily demonstrated. cycles shall be recorded. shall be demonstrated that the pressurization system will not create a hazard to personnel or an unsafe condition in the airplane if there is a loss of pressure in any one compartment. 4.2.2 Performance tests,-The following tests shall be conducted, in add
31、ition to any others deemed necessary, to demonstrate satisfactory performance of the cabin pressurizing and air conditioning system. During all test flights the cabin shall be observed for contamination and any occurrence shall be described in detail, Controls for the system shall be set as required
32、 for optimum performance, however, the exact use made of the controls during the flights shall be described in detail. Test data shall be recorded as specified in section 3. Take-off and accomplish a maximum-power climb to tbe normal cruise altitude. Data should be recorded beginning with the start
33、of the take-off run. Fly at normal cruise altitude with appropriate engine power settings until temperature conditions within the cabin reach stabilization. Determine the effect of changing the setting of the temperature control to points above and below the design setting. Record data until stabili
34、zation is obtained. ceiling, whichever is the highest. Operation of all equipment shall be observed and data recorded until stabilized conditions are obtained. safe altitude and fly at this altitude until stabilized conditions within the cabin are obtained. Data shall be recorded at sufficient inter
35、vals to permit an accurate evaluation of the performance of all equipment. data to show that the capacity and performance of the heating system is satisfactory, Demonstrate that the capacity of the heating system is adequate during a descent made with miniinum engine power settings. 4.2.2.7 Under th
36、e most critical combination of altitude and speed, record data to show that the capacity of the cabin ventilating system is satisfactory. On pressurized aircraft, this test applies to the auxiliary ram air ventilation system. Under the most critical combination of altitude and speed, obtain data to
37、show that the capacity of the cooling system is adequate. 4.2.1.4 Operation of the cabin safety valve with regard to the prevention of 4.2.1.5 It shall be demonstrated that failure of the power source used for The safe operation of air locks in pressurized aircraft shall be Pressure changes during d
38、ecompression and recompression 4.2.1.7 In aircraft containing two or more pressurized compartments, it 4.2.2.1 4.2.2.2 4.2.2.3 4.2.2.4 Increase the altitude of the airplane to the combat or service 4.2.2.5 Descend the airplane at the maximum permissable rate to the minimum 4.2.2.6 Under the most cri
39、tical combination of altitude and.speed, record 4.2.2.8 4.2.2.9 This test applies only to VF type aircraft. At the altitude where .- .-. .: . 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-18606( Aer ) maximum speed (Vmax) can be obtained, a
40、ccelerate the airplane at maximum rate to its maximum velocity and record data to define the performance of the cooling system during this transient condition. If it is practicable, maintain the airplane at maximum power long enough to obtain stabilized temperature conditions, or at least to establi
41、sh the trend of the cabin temperature rise. 4.2.2.10 If the airplane is equipped with two or more cabin pressurizing sources, one pressure source shall be directed away from the cabin or operation stopped in order to determine if design cabin differential pressure can be maintained at the normal cru
42、ise altitude. Proper operation of the air conditioning and pressure control system shall be demonstrated in this condition. 4.2.2.11 On aircraft equipped with combustion heaters, locate an atmos- pheric temperature condition which will require intermittent or low output operation of the heater(s) to
43、 satisfy cabin heat demands. Continue to fly the airplane under this condition until stabilization of cabin temperature is obtained. Observe cabin temperature to detect cyclic variation. 4.2.2.12 During flight at normal cruise altitude the performance of the ventilation provisions for the galley and
44、 sanitation areas shall be tested as specified in Section 3.2.2. 4.2.2.13 Heating and ventilating installationa in rotary wing aircraft shall be satisfactorily demonstrated during all directions of flight and during hovering. 4.2.2.14 Heating and ventilating systems installed In airships shall be de
45、monstrated satisfactorily for all conditions of flight, including hovering and tactical maneuvers. 4.3 Defogging and defrosting system tests for pressurized aircraft.-These tests shall be made when the sea level dew point temperature is as near as practicable to 85 degrees Fahrenheit, but no lower t
46、han 60 degrees Fahrenheit. The flights should be made during early morning or late evening when the dry bulb temperature is low. 4.3.1 Test procedure.rThe airplane shall be climbed to the lowest altitude at which a true atmospheric temperature of minus 65 degrees Fahrenheit exists. airplane shall lo
47、iter at this altitude, at the minimum engine power setting required to maintain level flight, for a period of 30 minutes. A maximum rate of descent dive with the lowest practicable engine power setting shall be accomplished to the safe minimum altitude. The airplane shall be descended through as muc
48、h cloud as possible, particularly at low altitude. The 4.3.2 maximum allowable speed. The above test shall be repeated with the dive being made at the 4.3.3 Tests shall be conducted with the system controls set for optimum performance, however, the exact use made of the controls during the flights s
49、hall be fully described. 4.3.4 The following test data shall be reported: Sea level dew point and dry bulb temperatures during test flights. Cabin temperatures at head and foot level taken at regular intervals during the flight. These tempera- tures must also be .recorded immediately before and after descent. Defogging air temperature and temperatures at various locations of the inner surface of the tramparancies. The condition of all transparancies during the flight. The condition shall be
