ELT transmitter Test


             Whenever the ELT is switched from “ON” to “ARM” a 406 MHz signal is transmitted, however, it is specially coded as a “Self-Test” signal that is ignored by the COSPAS-SARSAT satellites                
       Always perform the tests within the first 5 minutes of the hour. Notify any nearby control tower of your intentions.
              Do not allow test duration to exceed 5 seconds. A false alarm may be generated.
        Any time the ELT is activated, it is transmitting a 121.5 MHz distress signal. After approximately 50 seconds, a “live” 406 MHz distress signal is transmitted and is considered valid by the satellite system.
Self-Test
• Tune a receiver (usually the aircraft radio) to 121.5 MHz. Turn the ELT aircraft panel switch “ON” for about 1 second, then back to the “ARM” position. The receiver should voice about 3 audio sweeps.
• At turn-off (back to ‘ARM’ state) the panel LED should present 1 pulse (buzzer will not sound for 1 pulse). If more are displayed, determine the problem from the list below.
1 Flash – Indicates that the system is operational and that no error conditions were found.
3 Flashes – Bad load detected. Detects open or short condition on the antenna output or cable. These problems can probably be fixed by the installer.
􀂃Check that the RF cable is connected and in good condition. Perform continuity check of center conductor and shield. Check for a shorted cable.
􀂃Check for intermittent connection in the RF cable.
􀂃If this error code persists there may be a problem with the antenna installation. This can be checked with a VSWR meter. Check the antenna for opens, shorts, resistive ground plane connection.

4 Flashes - Low power detected. Occurs if output power is below approximately 33 dBm (2 watts) for the 406 signal or 17 dBm (50 mW) for the 121.5 MHz output.
􀂃Check coax and connections
􀂃Check antenna installation
􀂃Check that the frequencies are within acceptable limits

5 Flashes – Indicates the ELT was not programmed, or is incorrectly programmed. Does not indicate erroneous or corrupted programmed data.
6 Flashes – Indicates the G-switch loop between pins 5 and 12 at the D-sub connector is not installed. ELT will not activate during a crash.
􀂃Check that the harness D-sub jumper is installed by verifying less than 1 ohm of resistance between pins 5 and 12.

7 Flashes – Indicates that the ELT battery has too much accumulated operation time (> 1hr, see below). Battery may still power ELT; however, it must be replaced to meet FAA specifications. May also indicate damage to the battery circuit.
Self-Test Schedule -Artex recommends that the ELT be tested every 1-2 months. Follow the steps outlined above.
NOTE: The self-test time is accumulated in a register on the battery pack. The register records activation time in 30 second increments so all activations will count as at least 30 seconds, even if the actual time is much less. Total allowable time is 60 minutes as determined by FAR 91.207 and RTCA DO-204. After this time has been accumulated a 7-flash error will be presented after the self-test. The battery must be replaced at this point for the ELT to remain in compliance. Always follow ELT testing requirements per local or national

Comments

Post a Comment

Popular posts from this blog

Cessna 152 Magneto Check

MAGNETO CHECK. NEVER ADVANCE TIMING BEYOND SPECIFICATIONS IN ORDER TO REDUCE RPM DROP. Too much importance is being attached to RPM drop in single ignition. RPM drop on single ignition is a natural characteristic of dual ignition design. The purpose of the following magneto check is to determine that all cylinders are firing. If all cylinders are not firing, the engine will run extremely rough and cause for investigation will be quite apparent. The amount of RPM drop is not necessarily significant and will be influenced by ambient air temperature, humidity, airport altitude, etc. In fact, absence of RPM drop should be cause for suspicion that the magneto timing has been bumped up and is set in advance of the setting specified. Magneto checks should be performed on a comparative basis between individual right and left magneto performance. a. Start and run engine until the oil and cylinder head temperatures are in normal operating ranges. b. Advance engine speed to 1700 RPM. c. Tu
Read more

Brake System Cessna 172

                             BRAKE SYSTEM -MAINTENANCE PRACTICES              1. Description and Operation A. The hydraulic brake system is comprised of two master cylinders, located immediately forward of the  pilot’s rudder pedals, brake lines and hoses, and single-disc, floating cylinder brake assemblies located at  each main landing gear wheel. B. The parking brake system is comprised of a pull-type handle and mechanical connections which are  linked to the rudder pedal assembly. Pulling aft on the brake handle applies mechanical pressure to the  rudder pedals, activating the brakes and locks the handle in place. Turning the handle 90 degrees will  release the parking brake and allow for normal operation through the rudder pedals. C. Brake operation is accomplished by pushing on the upper part of each rudder pedal. This motion is  mechanically transmitted to the respective brake master cylinder, and through fluid-carrying lines out to  the brake assembly where fluid pressure
Read more

McCauley Propeller Installation fixed pitch

Image
Propeller Installation for all fixed pitch propellers (except 1A162 model propellers).                   WARNING: MAKE SURE THE MAGNETO IS GROUNDED BEFORE INSTALLING  THE PROPELLER OR CONNECTING EXTERNAL POWER.                NOTE: McCauley recommends that propeller mounting nuts (if applicable) be replaced at each  propeller installation, whenever possible. However, nuts may be reused providing the threads are in good condition and the locking material prevents turning of the nut on the  stud by hand. Propeller mounting bolts must be magnetic particle inspected in accordance  with ASTM E-1444 or replaced whenever the propeller is removed from the engine.                NOTE: The aircraft maintenance manual or STC installation instructions should always be  consulted for any specialized procedures applicable to a specific aircraft. Various spinner arrangements not manufactured by McCauley may be used which require additional procedures. (1) Make sure the mating surfaces of t
Read more