Technology Notebook ContentsEffective Date: 15 June 98
Flight Tests
Upon completing the development testing and comfirming that production hardware is installed in the demonstration aircraft, flight tests are required to show that the air data system conforms to the current standards of accuracy and operation suitability.
REQUIREMENTS
The pitot-static system should meet all Military Specification 26292C and FAR 25.1323 and 25.1325 requirements in regards to airspeed position error, throughout the speed and gross weight range of the aircraft, for clean and flaps extended configurations. However, MIL-P-26292C and FAR 25.1325 requirements in regards to altitude position error are exceeded for some systems and configurations at extreme weights, airspeeds, altitudes, or a combination thereof. No Mil-Spec requirements are applicable to the takeoff or approach configurations.
For the landing configuration, altitude position error should not exceed the +30 foot limit specified by MIL-P-26292C.
The FAR 25.1325(e) altitude position error requirement not to exceed +30 feet per 100 knots above 1.3Vs for all flaps extended configurations is requiredto be satisfied for the pilot's and copilot's system.
The FAR 25.1325(e) altitude position error requirement not to exceed +30 feet per 100 knots below 1.8Vs for flaps retracted configuration is not fully satisfied for the copilot's and navigator's systems. The system should not exceed the +30 foot limit at all altitudes. Reference is made to the Code of Federal Regulations 14 - Aeronautics and Space, Federal Aviation Administration, Parts 1 to 59, Revised 1 January 1985.
Dynamic Flight Condition Check
A series of sideslips, pullups, and pushovers are performed to evaluate the pitot-static system under dynamic flight conditions.
TEST CONDITIONS (Typical)
Depending upon the speed spectrum of the test aircraft the dynamic flight checks are performed at the following test conditions:
Maneuver / Airspeed / Altitude
10 deg Right Yaw / 170 KIAS / 10,000 Feet
10 deg Left Yaw / 170 KIAS / 10,000 Feet
Pullup / 140 KIAS / 10,000 Feet
Pullup / 180 KIAS / 10,000 Feet
Pullup / 220 KIAS / 10,000 Feet
Pushover / 140 KIAS / 10,000 Feet
Pushover / 180 KIAS / 10,000 Feet
Pushover / 220 KIAS / 10,000 Feet
(DESIRED) RESULTS
YAWING
Military specifications 26292C requires that the airspeed indication shall not differ from straight-flight conditions by more than + 2 knots when the aircraft is yawed approximately 10o right or left in the approach configuration. The altimeter indication shall not differ from the straight-flight conditions by more than a + 20-foot altitude. Results of the 10o yawing maneuvers for the pilot's and copilot's system are typically presented as time histories.
PULLUPS
Military Specification 26292C requires that during an abrupt pullup from level flight, the rate of climb indicator shall indicate up without excessive hesitation and shall not indicate down before it indicates up.
Abrupt pullups were performed at 10,000 feet for airspeeds of 140, 180, and 220 knots. A positive rate of climb was observed by the flight test crew for all runs. Time histories for the pilot's and copilot's system are typically presented.
PUSHOVERS
Military Specification 26292C requires that during an abrupt pushover from level flight, the rate of climb indicator shall indicate down without excessive hesitation and shall not indicate up before it indicates down.
Abrupt pushovers were performed at 10,000 feet for airspeeds of 140, 180, 220 knots. A negative rate of climb was observed by the flight test crew for all runs. Time histories for the pilot's and copilot's system are typically presented.
POINTER OSCILLATION
No pointer oscillation exceeding 3 knots should be observed while maneuvering in rough air.
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