trev130eng Posted July 21, 2010 Share Posted July 21, 2010 I have an on-going problem with the ice detection system switching it itself on in no icing conditions. I've swapped out everything in the system now and all wiring checks are good. The only spare ice detectors i have access to are coming from an aircraft where the system is known not to have worked in some time. In order to order new detectors i need to prove my current ones are unserviceable. Is there any bench check with a multimeter i can carry out to check the serviceability of ice detectors? Quote Link to comment Share on other sites More sharing options...
Nc97 Posted July 21, 2010 Share Posted July 21, 2010 I have an on-going problem with the ice detection system switching it itself on in no icing conditions. I've swapped out everything in the system now and all wiring checks are good. The only spare ice detectors i have access to are coming from an aircraft where the system is known not to have worked in some time. In order to order new detectors i need to prove my current ones are unserviceable. Is there any bench check with a multimeter i can carry out to check the serviceability of ice detectors? With a multimeter, and a freezer....Check the circuit (well, really the thermostat); circuit must close on decreasing temperature of 52 plus or minus 5 degrees F. Circuit must open on an increasing temperature of 67 plus or minus 8 degrees F. I have repaired and overhauled a lot of ice-detectors (092-000-001 and 575-315), but can't say I have ever seen one turn on by itself. The only other possibility I can think of is that the tension spring is screwed down to tight, setting the switch nipple to close to the diaphragm, activating it inconsistently. Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted July 21, 2010 Share Posted July 21, 2010 Hi Guy's, got a problem with the ice detection system i can't seem to resolve. Is this the same aircraft as discussed on the above thread? Mechanical or solid state detectors? Quote Link to comment Share on other sites More sharing options...
trev130eng Posted July 21, 2010 Author Share Posted July 21, 2010 We have mechanical ice detectors. 20 flights this week alone (paratroops) the ice detection system is turning itself on almost constantly. I am a C-130 ground test engineer. During ground test of the system, going to between reset and normal during test with the engines running the orange light should go on and off during the test cycle. This has never happenned. The on light goes off and stays off during the test cycle. Any help will be most appreciated. Flying with the a/c nearly everyday and seeing the problem. Quote Link to comment Share on other sites More sharing options...
trev130eng Posted July 21, 2010 Author Share Posted July 21, 2010 Been flying nearly everday. Even at 20,000 ft the temp is only minus ten with no icing. Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted July 22, 2010 Share Posted July 22, 2010 After takeoff pull the IGN control cber for # 2 and leave it pulled (untill you land or need to pull the fire handle OR get the ice detection turns itself ON) See if the ice detection comes on in no ice condition. If it does reset #2 IGN control Cb and pull #3 and leave it pulled (untill you land or need to pull the fire handle) See if the ice detection comes on in no ice condition. You should be able to see which one (2 or 3) is tripping your system. do your engine inlets open when the ice detection turns itself on? Quote Link to comment Share on other sites More sharing options...
tenten Posted July 24, 2010 Share Posted July 24, 2010 Hi Tref, Have you changed Auto De-icing relay? If not, give a try, I am saying that based on system electrical circuit. Quote Link to comment Share on other sites More sharing options...
trev130eng Posted July 25, 2010 Author Share Posted July 25, 2010 We have changed everything now. Keeps coming back to bad detectors. Quote Link to comment Share on other sites More sharing options...
jetcal1 Posted July 26, 2010 Share Posted July 26, 2010 Are you using the same test equipment on each check? Do you have another aircraft you can run the same checks on? If so, when used to test other components are they passing? Quote Link to comment Share on other sites More sharing options...
trev130eng Posted July 28, 2010 Author Share Posted July 28, 2010 All checks being carried out on engine ground runs. This is the only aircraft available. Quote Link to comment Share on other sites More sharing options...
jetcal1 Posted July 28, 2010 Share Posted July 28, 2010 (edited) Trev, Keep in mind, I AM NOT a C-130 mech. My only involvement here is due to working for a company that manufactures C-130/T56 test gear. (Disclaimer) When multiple failures of the same system or component have come up before; 1. We have had a bad batch of parts come through the system 2. There has been a change to the component limits (specifications) by the manufacturer without updating the T.O. (Causing the unit or system or test equipment to fail the unit for being out of limits.) 3. Bad test equipment I’m not sure if this will help you, but it’s food for thought. As an aside, corroded sockets and pins in a system create some real troubleshooting nightmares. Are you checking resistance as well as continuity? Edited July 29, 2010 by jetcal1 Added test equipment to para 2. Quote Link to comment Share on other sites More sharing options...
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