FUEL TEMP Warning

Any DA42 related topics.

Moderators: Rick, Lance Murray

User avatar
Wilfried
3 Diamonds Member
3 Diamonds Member
Posts: 77
Joined: Fri May 02, 2014 8:14 pm
First Name: Wilfried
Aircraft Type: DA42NG
Aircraft Registration: OEFSJ
Airports: EDMA
Has thanked: 4 times
Been thanked: 29 times

FUEL TEMP Warning

Post by Wilfried »

Yesterday I had a confusing failure indication: Flight duration was 2:00. After approx. 1:30 I got a red R FUEL TEMP indication on the PFD. A look into the engine parameters showed a quickly rising fuel temperature to a maximum of 105 degrees. Emergency checklist advised to reduce engine power. I reduced from 75% to 55%. Fuel temperature decreased to around 60 degrees. Then I switched the fuel selector of the right engine to the left side. Temperature on the RH side fell again to around 46 degrees and remained at this level until landing. I am not an engineer, but it doesn't look like a sensor problem. Any of you have an idea?
IMG_2573.JPG
IMG_2571.JPG
User avatar
Aart
4 Diamonds Member
4 Diamonds Member
Posts: 447
Joined: Fri Jun 18, 2010 4:27 pm
First Name: Aart
Aircraft Type: DA42
Airports:
Has thanked: 21 times
Been thanked: 22 times

Re: FUEL TEMP Warning

Post by Aart »

Yes, this looks like a sensor problem to me, although obviously not a completely failed sensor.
Good thing you did a cross-feed and waited to see what that would bring. The actual fuel temp on the ride side will have dropped a lot more than what the sensor finally read, 46 degrees. It should have read lower than 27 degrees, the temp on the left side, because the fuel on the right side was no longer heated by the RH engine. It should have gradually reduced to ambient temperature, assumed to be relatively low where you were flying?
Aart
DA42.332 PH-CCD LESB (Palma de Mallorca, Spain)
User avatar
oamir
2 Diamonds Member
2 Diamonds Member
Posts: 27
Joined: Tue May 10, 2016 6:29 pm
First Name: ofer
Aircraft Type: DA62NG
Aircraft Registration: 4XCXR
Airports: LLHZ
Has thanked: 3 times
Been thanked: 11 times

Re: FUEL TEMP Warning

Post by oamir »

Hello,

had the same problem on the same airplane model a couple of months ago, the shop just clean well the sensor and all was back on track :) good luck

ofer
User avatar
Wilfried
3 Diamonds Member
3 Diamonds Member
Posts: 77
Joined: Fri May 02, 2014 8:14 pm
First Name: Wilfried
Aircraft Type: DA42NG
Aircraft Registration: OEFSJ
Airports: EDMA
Has thanked: 4 times
Been thanked: 29 times

Re: FUEL TEMP Warning

Post by Wilfried »

Today I carefully checked the RH nacelle back side and fuel vents, if they were blocked or something. Than I did a ground run up watching, if fuel temperatures rise simultaneously. Noticed nothing special. Then I flew around one hour. Everything looked normal. Will talk to my maintenance shop tomorow.

@ Aart - FL100
User avatar
Aart
4 Diamonds Member
4 Diamonds Member
Posts: 447
Joined: Fri Jun 18, 2010 4:27 pm
First Name: Aart
Aircraft Type: DA42
Airports:
Has thanked: 21 times
Been thanked: 22 times

Re: FUEL TEMP Warning

Post by Aart »

Pls report back, always nice to learn..
Aart
DA42.332 PH-CCD LESB (Palma de Mallorca, Spain)
User avatar
Wilfried
3 Diamonds Member
3 Diamonds Member
Posts: 77
Joined: Fri May 02, 2014 8:14 pm
First Name: Wilfried
Aircraft Type: DA42NG
Aircraft Registration: OEFSJ
Airports: EDMA
Has thanked: 4 times
Been thanked: 29 times

Re: FUEL TEMP Warning

Post by Wilfried »

Hi Aart, my maintenance believes it is a problem with the RH fuel cooler system and nothing wrong with indication or sensor . The fuel vents could have been blocked by ice... The flight, on which it happened was for more than 1h in IMC conditions, temps around 0 degrees. I was frequently checking inner and outer wings, spinner, air inlets for icing during the flight. Could not see any build ups. Mmh, I don't know. During the last flight all systems worked ok. Will fly again on Friday - looks like severe VMC 8) . See what will happen.

btw - thanks for information and recommendations for my flight to Mallorca. I felt very prepared and all worked out well. Staff at the airfield very friendly and helpful.
klang
2 Diamonds Member
2 Diamonds Member
Posts: 32
Joined: Tue Jul 29, 2014 2:24 pm
First Name: karl
Aircraft Type: DA42
Aircraft Registration: DGGWU
Airports: LSZC
Has thanked: 3 times
Been thanked: 7 times

Re: FUEL TEMP Warning

Post by klang »

It appears more of a problem with the RH fuel cooler, not the sensor.
Assuming the RH fuel cooler was blocked (or not functioning for whatever reason) then the fuel returned from the HP fuel injection entered the RH wing tank at temperatures much higher than 46°C (not sure of exact fuel temp coming from the HP injection common rail), resulting in increasing temperature of the entire fuel contained in the RH wing tank. I must admit, 106°C fuel temperature is extreme, but I have noticed that indicated fuel temp changes rapidly up or down during cross feed. This suggests the temp sensor is located close to where the return fuel line connects to the wing tank, i.e. the indicated 106°C did not tell the real average temp of the entire fuel in the tank but only the temp near the tap-in point of the return line.
After RH engine cross-feed to LH tank, the temperature in the RH wing tank remains high and cools off gradually.
So, the 46°C RH wing tank temperature you observed after landing could well be indication of a fuel cooler problem.
User avatar
Wilfried
3 Diamonds Member
3 Diamonds Member
Posts: 77
Joined: Fri May 02, 2014 8:14 pm
First Name: Wilfried
Aircraft Type: DA42NG
Aircraft Registration: OEFSJ
Airports: EDMA
Has thanked: 4 times
Been thanked: 29 times

Re: FUEL TEMP Warning

Post by Wilfried »

FYI - 7 hours of flight time after the abnormal high fuel temps and it didi not happen again. For your reference Temps at FL95 at OAT 7 degree Celsius were 28 LH and 29 RH side and stable. Still no idea what the root cause was (ice?), nevertheless fuel cooling seem to work properly now.
42.N020
User avatar
Rmateu
2 Diamonds Member
2 Diamonds Member
Posts: 18
Joined: Thu Aug 13, 2015 6:50 pm
First Name: Roberto
Aircraft Type: DA42-VI
Aircraft Registration: YV3313
Airports: SVCS
Been thanked: 6 times

Re: FUEL TEMP Warning

Post by Rmateu »

Hi, I have the same problem on my last flight. climbing I got a Fuel temperature warning on the RH. However, having read before the flight the problem on the forum. I took my time to review the situation. First, how I manage the problem and second my thoughts on the problem. I did a cross-feed for that engine and immediately the temperature went down. I wait a couple of minutes and establish the normal feeding, but the temperature went up again. thus I put both engines on cross-feed until level flight and then I returned the feeding to normal once I got to level flight and this time the temperatures stayed on the green side for the rest of the flight.
One thing that I notice before the flight was the temperature were not the same on the indicator when I star the master. something that is not logical, since without a source of heat, the temperature on both tanks should be the same. Second, if the source of the problem is the fuel cooler, as soon I did the cross-feed on the other engine, the fuel temperature should had gone up, since I should be drawing hot fuel from the RH tank to the LS engine something that did not happen.
I am draw to believe that the source of the problem is the sensor. Next week the plane is going to the shop and I will have more news.
PD the flight was in the Caribbean were outside temperature was in the 30 C and level at F115 was +9C so ice was not a factor
User avatar
Wilfried
3 Diamonds Member
3 Diamonds Member
Posts: 77
Joined: Fri May 02, 2014 8:14 pm
First Name: Wilfried
Aircraft Type: DA42NG
Aircraft Registration: OEFSJ
Airports: EDMA
Has thanked: 4 times
Been thanked: 29 times

Re: FUEL TEMP Warning

Post by Wilfried »

Hi "Rmateu",
Would be interested to get your feedback after your maintenance had a look to the issue. I did not experience a problem after I wrote the report above. Since you are writing that indications were different at start up of the engines, I suppose it might be an engine problem (envy you for flying in the Caribbean - these days it started snowing here :shock:
42.N020
Post Reply