TECHNISONIC INDUSTRIES LIMITED
www.til.ca
TFM-30 Installation & Operating Instructions
TiL 98RE244 Rev n/c Issue 9
A-1
APPENDIX A– POST INSTALLATION EMI TEST INSTRUCTIONS
PURPOSE
The purpose of this test is to identify any interference that the TFM-30 may cause with
existing aircraft systems.
TEST CONDITIONS
The TFM-30 should be installed and function tested. The antenna VSWR should be
checked. A forward/reverse power check with a in-line wattmeter should show no more
than 10% reflected power.
METHODOLOGY
Most of the EMI tests can be accomplished on the ground. In some cases, flight testing is
required or easier. If the aircraft is approved for IFR operations, then it is mandatory that
interference between the TFM-30 and the approach aids be checked in flight.
The GPS should be operational and navigating with at least the minimum compliment of
satellites. The VHF comm should be set to the frequencies indicated with the squelch open.
VOR/ILS/GS receivers should be set to the frequencies indicated and selected for display. If
possible, set up a VOR/ILS ramp test set on the frequencies indicated and adjust the output
until the flags are out of view. The transponder and encoder should be monitored with ramp
test equipment. If possible set the ADF to a nearby navigation station.
Modulate the TFM-30 transmitter on the indicated frequencies for at least 20 seconds.
Observe the GPS for any degradation in satellite status or availability or flags. Listen for any
noise or detected audio signals on the VHF comm(s). Listen for any noise or detected audio
signals on the VOR/LOC receiver audio. Look for any moment of flags or needles on the
VOR/LOC/GS navigation display(s).
List the power plant, fuel and other electric instruments in the chart provided and note any
anomalies that occur while transmitting. Assess the results.
If the aircraft is equipped with an autopilot or a stability augmentation system, then test fly
the aircraft and verify that the operation TFM-30 does not have adverse effects on these
systems. After checking for gross effects at a safe altitude, fly an approach with each of
the different navigation systems coupled to the autopilot (ILS, GPS, etc.) and look for any
anomalies.
RESULTS
If the installed system passes all of the applicable EMI tests, then no further action is
required. If interference is observed then the interference must be assessed against the
appropriate standards of airworthiness for the system in question. For example it is
permissible for a VFR certified GPS to lose navigation capability while the TFM-30 is
transmitting, providing that it recovers properly and promptly, but it is not permissible for an
IFR Approach certified GPS to be affected in the same way.
A complete discussion of all the standards of airworthiness to be applied in assessing EMI
effects is beyond the scope of this document.
