Civil Aviation Order 108.56 Instrument 2007 (Cth)

I, WILLIAM BRUCE BYRON, Director of Aviation Safety, on behalf of CASA, make this instrument under regulation 38 of the Civil Aviation Regulations 1988.

[Signed Bruce Byron]

Bruce Byron
Director of Aviation Safety and
   Chief Executive Officer

19 December 2007

Civil Aviation Order 108.56 Instrument 2007

1          Name of instrument

            This instrument is the Civil Aviation Order 108.56 Instrument 2007.

2          Commencement

            This instrument commences on the day after it is registered.

3          New Civil Aviation Order 108.56

            Civil Aviation Order 108.56 is repealed and a new Civil Aviation Order 108.56 substituted as set out in Schedule 1.

Schedule 1          Civil Aviation Order 108.56

Specification — testing of specified aircraft instrument

1          Application

   1.1     This Civil Aviation Order specifies test procedures and requirements for accuracy of airspeed indicators, pressure-type altimeters, pitot-static systems and fuel quantity gauges installed, or to be installed, in aircraft intended for operations in V.F.R. or night V.M.C. conditions and applies in such circumstances as may be directed by the Director or an authorised person under the Civil Aviation Regulations 1988.

2          Test conditions

   2.1     The tests mentioned in this Order may be made:

(a)   either on, or away from, the aircraft; and

(b)   under ambient conditions, and vibration may be applied.

3          Test procedure and accuracy

   3.1     Airspeed indicators

            Airspeed indicators must be tested against an appropriate test instrument. The scale errors at the major graduations of the scale must not exceed ± 4 knots up to the maximum speed of the aircraft, when tested first with the pressure increasing and then with the pressure decreasing. Operation must be smoother and continuous.

   3.2     Altimeters

            Altimeters must be tested for diaphragm errors against an appropriate test instrument from sea level to the maximum operating height of the altimeter or to 21 000 feet. Errors must not exceed:

(a)   those specified by the instrument manufacturer; or

(b)   ± 100 feet or 3% of the indicated altitude, whichever is the greater.

Note   A sensitive altimeter regularly checked to ensure that it complies with the calibration tolerances specified in Appendix E of FAR Part 43 is acceptable as meeting the requirements of this paragraph for an appropriate test instrument.

   3.3     Pitot-static systems

      (1)  The pitot system must be tested for leaks by applying a pressure at the pitot head sufficient to cause the airspeed indicator to read 120 knots. There must be no sign of restrictions in the piping during application of the pressure and no decrease in the reading when the system is sealed for at least 10 seconds.

      (2)  The static system must be tested for leaks by applying sufficient suction to the system to cause the airspeed indicator to read 85 knots. The system must then be sealed. The reading of the airspeed indicator must not decrease by more than 4 knots within 10 seconds.

   3.4     Fuel quantity gauges

      (1)  The indicated quantity of fuel must equal the actual fuel in the tank less the unusable quantity of fuel, subject to the tolerances mentioned in this paragraph.

(2)  Fuel quantity gauges must be checked for accuracy at all major graduations.

(3)  Scale errors at empty must not exceed + 0.5% or – 5% of the nominal tank capacity except that for systems where it is impracticable to correct the empty reading, a tolerance of + 0.5% or – 8% will be acceptable.

(4)  Where scale errors or the ungaugeable quantity of fuel exceeds ± 5% of the nominal tank capacity or the gauge is calibrated in fractions of tank capacity, a placard must be displayed adjacent to the indicator showing the corrected readings at all major graduations and the ungaugeable quantities of fuel.

(5)  Fuel quantity gauges must be checked with the aircraft in level flight attitude. Electrically operated gauges must have normal system voltages applied. The fuel quantity at each calibration point should be made either by measurement of the fuel added to the tank or a dip or drip stick previously calibrated for the tank in question.

(6)  The motion of the gauge during test must be smooth and continuous.