bruno_Tuga Posted March 22, 2013 Share Posted March 22, 2013 I´m working in a c130 H, s/n 5115, equipped with digital fuel indication. During normal flight, the pilots loose all fuel indication minus in the EXT LH and #3, whem they set the aircraft to a high velocity. In the begening they said that it was with a certain atitude. But after a new flight test, they saw that in all atitudes that they give to the aircraft the problem is the velocity. The indication goes off, like losing power, and goes on with a smaller velocity. Can someone help? Thank You Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted March 23, 2013 Share Posted March 23, 2013 So the indicators remain Blank (off) NO indications except #3 and Rt Ext at airspeed above_____KIAS? (Same TAS or same IAS) Or do they go to 0.00? What does the Totalizer do? Blank or still reads same fuel quantity or less? Any other indications like TIT Flags in view? Quote Link to comment Share on other sites More sharing options...
bruno_Tuga Posted March 23, 2013 Author Share Posted March 23, 2013 I´m trying to talk with the pilot to now more details, but i already now that: - IAS was 222 kts - The fault indicators went off, no indication, like missing power Soon as i now more details i´ll post. Thank you Quote Link to comment Share on other sites More sharing options...
bruno_Tuga Posted March 23, 2013 Author Share Posted March 23, 2013 So the indicators remain Blank (off) NO indications except #3 and Rt Ext at airspeed above_____KIAS? (Same TAS or same IAS) Or do they go to 0.00? What does the Totalizer do? Blank or still reads same fuel quantity or less? Any other indications like TIT Flags in view? More information about the problem: - The indication went off with aircraft in level flight 17000 ft 240 kts and 3000 ft 220 kts. This is TAS and not IAS has i said in the last post - The totalizer went off, no power . Start indicating when all the other indication came on - The pilot didn t saw na failure in other inditations (TIT), everything was good except some fuel indications. We already check the bondings off the indicators. The values of wiring and tanks are OK. Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted March 26, 2013 Share Posted March 26, 2013 Check the Fuel Quantity CB bus bar. The screws may be loose or the bar cracked... Also check the wire bundle where and as the CB panel closes... This is very strange... Quote Link to comment Share on other sites More sharing options...
bruno_Tuga Posted March 26, 2013 Author Share Posted March 26, 2013 Check the Fuel Quantity CB bus bar. The screws may be loose or the bar cracked... Also check the wire bundle where and as the CB panel closes... This is very strange... We think that we found the problem. It seems that a voltage surge supressor in the pilot CB, near the fuel indication CB, had the wiring loose. Because of that whem there was a high voltage peak, the indicators where not protected. We read this in a USAF manual. But you may ask, why there were two that didn´t went off? We think that is because of the type (p/n) of the indicator installed. The indicators in #3 and Ext LH have the same p/n, diferent from the other six. Tomorrow the aircraft will fly and i will them tell you if we are right. Thank you NATOPS1 for you help. [ATTACH=CONFIG]3350[/ATTACH] Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted March 27, 2013 Share Posted March 27, 2013 Hope your problem is fixed... Quote Link to comment Share on other sites More sharing options...
bruno_Tuga Posted March 28, 2013 Author Share Posted March 28, 2013 Bad news, today... the problem ins´t solved. We did 3 flight´s today and still have the problem. During the day we found some more clues: - During flight at high altitute, 16000 fts the problem doesn´t happen - Fly level 500- 900 Fts, TAS more than 240 kts, the problem happen - If during the low altitude flight we change from Ess AC to inverter, the problem doesn´t happen, the indication is OK - We have diferent P/N in the indicators, those who are equal go inop. The one that is alone work good. In other aircraft we have diferent P/N in the indicators and never had this kind of problem - We cheked all the wiring in the pilots CB, and relays behind the CB´s, all good - We change two relays (see schematic) We think that should be something in the power bus... Someone want´s to give a attempt??? Thank You[ATTACH=CONFIG]3353[/ATTACH] Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted March 28, 2013 Share Posted March 28, 2013 This is why I asked about the TIT gage flags (off indicatiors) I think(thought) it was a power issue at the beginning. Check the voltage on #2 Gen (A Phase) at the higher airspeed when the power goes out to the gages it must be dropping. Turn off the #2 Gen, #1 Gen should power your Ess AC and see if your problem is resolved. If it is resolved I think you have a wing flex issue with the #2 Gen A phase feed line. If not turn on the inverter which provides power to the AC Inst EFC bus and is inside the aircraft so no "Speed" relationship. Quote Link to comment Share on other sites More sharing options...
bruno_Tuga Posted March 28, 2013 Author Share Posted March 28, 2013 This is why I asked about the TIT gage flags (off indicatiors) I think(thought) it was a power issue at the beginning. Check the voltage on #2 Gen (A Phase) at the higher airspeed when the power goes out to the gages it must be dropping. Turn off the #2 Gen, #1 Gen should power your Ess AC and see if your problem is resolved. If it is resolved I think you have a wing flex issue with the #2 Gen A phase feed line. If not turn on the inverter which provides power to the AC Inst EFC bus and is inside the aircraft so no "Speed" relationship. The TIT gauge were ok. I forgot to tell that we made that test od the GEN. During flight we turn off the gen #2, and the problem happened with the other 3 Gen in the BUS. I dind´t understand clear what is your ideia and you say: If it is resolved I think you have a wing flex issue with the #2 Gen A phase feed line. If not turn on the inverter which provides power to the AC Inst EFC bus and is inside the aircraft so no "Speed" relationship. Thank you, again. Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted March 28, 2013 Share Posted March 28, 2013 Ok... #2 Gen Off same problem. So Not a gen Issue its a ESS AC suppy to AC Inst EFC Bus issue. Inverter ON no problem. Your wiring to your instruments is good, check all your connections from the Normal power fail Cb to Power relays. Changed Power relays #1 and #2? (They are denergized to allow ESS AC to power the AC Inst EFC Bus so I hope it works but not sure it will) Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted April 4, 2013 Share Posted April 4, 2013 ANy update on this issue? Quote Link to comment Share on other sites More sharing options...
steve haigler Posted April 24, 2013 Share Posted April 24, 2013 Reading your message traffic, Was an electrical component or elec. maintenance done prior to the prob.? Look for compatability of parts. We had an elec prob on a H2, the gen was changed also the compatable GCU. They must match. I think your on the right track with the suppressor, that is what directly protects the digital gages. Just a thought. Steve Quote Link to comment Share on other sites More sharing options...
steve haigler Posted April 29, 2013 Share Posted April 29, 2013 Another check would be the fuel tank compensators. Steve Quote Link to comment Share on other sites More sharing options...
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