Bond ground all UK EC135s
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Ok, it may be confirmed now that more than one have been found with the same fault, so why are we still flying with only an additional limit? Ground them, check them, fix them, fly them.
That should take up most of the weekend and it is the Christmas season after all.
The point I was trying to make was why only impose a limit of 100kg? Why not get them all checked, and if ECUK refuse to check them all without costs, then ground them until ECUK acknowledge there may be a problem fleet wide. If NPAS feel there is any doubt, which they obviously do to impose additional limits, then as a duty of care they should not be allowing their staff to fly them in the first place.
That should take up most of the weekend and it is the Christmas season after all.
The point I was trying to make was why only impose a limit of 100kg? Why not get them all checked, and if ECUK refuse to check them all without costs, then ground them until ECUK acknowledge there may be a problem fleet wide. If NPAS feel there is any doubt, which they obviously do to impose additional limits, then as a duty of care they should not be allowing their staff to fly them in the first place.
2F1B,
NPAS Aircraft underwent a "Fuel System Confidence Check" today. Our current steed passed and we have been back to normal since I came on shift this evening. Have heard all the other aircraft in the region operating normally as well.
PS2A95BRAS
NPAS Aircraft underwent a "Fuel System Confidence Check" today. Our current steed passed and we have been back to normal since I came on shift this evening. Have heard all the other aircraft in the region operating normally as well.
PS2A95BRAS
SIN No. 2673-S-28
SUBJECT: FUEL SYSTEM
Information concerning LOW FUEL warning
Applicability EC135 T1, T2, T2+, P1, P2, P2+, 635 T1, 635 T2+, 635 P2+ MBB BK117 C-2
Eurocopter has been informed by Bond of an issue involving the fuel indication system on one of its
EC135 EMS aircraft during normal operation. Following this incident, tests performed on EC135 have
revealed supply-tank fuel gauging errors on some aircraft.
The first analysis shows that the indication of the fuel quantity in the supply tanks could be
overestimated. All crews should be aware that in the worst case a red warning LOW FUEL 1/2 could
appear without any amber FUEL caution before.
The red LOW FUEL 1/2 warnings are generated by an independent switching logic with separate
sensors in each supply tank. The red LOW FUEL 1/2 warning lights continue to operate correctly
even if the fuel gauging is inaccurate.
Therefore we want to remind you that:
• After illumination of LOW FUEL warnings the procedure iaw. the Flight Manual must be strictly
complied with, notwithstanding of the fuel quantity indication.
In addition we want draw attention to the proper airmanship iaw. Air Ops NCC.OP.131 “Fuel and oil
supply — helicopters” and NCC.OP.205 “In-flight fuel management” to ensure situational awareness
concerning fuel usage and flight time left.
Furthermore, we want to remind you of Information Notice 2535-I-28 “Notes about possible water
contamination of the fuel system”.
SIN No. 2535-I-28
SUBJECT: FUEL SYSTEM
Water contamination of the Fuel System
Applicability EC135 T1, T2, T2+, P1, P2, P2+, 635 T1, 635 T2+, 635 P2+ MBB BK117 C-2
EUROCOPTER has been informed about several fuel quantity indication failures. Following the
replacement of the affected fuel probe, the indication returned to normal and the functional check of the
fuel quantity indication system has been performed successfully.
When the subject probes have been returned to EUROCOPTER for repair, the probes showed no
external damage or contamination within the two concentric metal tubes and most of the probes have
been tested, with the result, “no fault found” (NFF). To investigate the reason for these NFF’s
EUROCOPTER performed several tests to simulate the failures. As a result from these tests, the most
probable root cause is contamination of the fuel probe with water.
These tests have shown - when water is entering the space between the two concentric metal tubes of
the probe - it will decrease the output signal (frequency) of the probe. In case of a high concentration of
water, the frequency can decrease to such a level that the CAD recognizes the probe as failed –
showing either an F QTY DEGR or F QTY FAIL caution on the CAD. Also there is a potential risk that the
CAD shows a higher fuel quantity level compared to the actual fuel level within the fuel tank system.
In addition, customers have reported, when removing the defective sensor from the helicopter, that after
removing the water by the use of shop air and warming up the sensor for a certain period of time, the
sensor has been working again without any fault.
It should be noted that even for operators that regularly drain the fuel tanks, a couple drops of water
concentrated between the metal tubes of the sensor may be enough to affect the signal.
There are several possibilities for the fuel system to be contaminated with water:
· Condensation within the fuel tank system. This is mainly caused when the fuel tanks are not
completely filled and the helicopter is parked outside and/or is exposed to great changes in
temperature
· Heavy rain during refueling of the helicopter – water is entering through the filler neck
· Contaminated fuel from the source – for example fuel truck, tank, supply system or barrels
· For EC135 when performing an engine compressor wash, the water from the combustion
chamber is drained into the drain bottle. On some helicopters there is a chance that water from
the drain bottle is sucked into the engine fuel system via the Fuel Control Unit. Operating the
prime pumps prior to the next engine start will allow the water to enter the helicopter fuel system
through the fuel return line and the fuel expansion box. From the fuel tank expansion box the
water will then flow back into the RH Supply Tank.
Therefore, as explained in the AMM Task 71-65-00, 7-1, it is recommended to follow the procedure and
to disconnect the combustion chamber drain tube before prior to starting the compressor wash process.
Due to the reason mentioned above, EUROCOPTER wants to point out the importance of keeping the
fuel system free of water and other contamination. When draining the fuel system, in reference to the
documents listed below, it must be performed before the helicopter is moved, in order to allow the
maximum amount of water to be drained from the tank.
EC135
AMM, Chapter 12-30-00, 3-5
MSM, Chapter 05-25-00, 6-1
FLM, Section 4 – Preflight Check
FLM, Section 8.3 – Drainage Procedure
BK117C-2
AMM Chapter 12-30-00, 3-16
MSM, Chapter 05-25-00, 6-1
FLM, Section 4 – Preflight Check
FLM, Section 8.3 – Drainage Procedure
In addition EUROCOPTER wants to point out that water – if not drained from the fuel system – can
cause different malfunctions within the fuel and engine system.
If there is doubt that the fuel system is free of water, EUROCOPTER recommends to take a fuel sample
from the helicopter tank system and to test it for the presence of water by using commercially available
Test Strips, for example the SHELL Water Detectors or another commercially available product.
SUBJECT: FUEL SYSTEM
Information concerning LOW FUEL warning
Applicability EC135 T1, T2, T2+, P1, P2, P2+, 635 T1, 635 T2+, 635 P2+ MBB BK117 C-2
Eurocopter has been informed by Bond of an issue involving the fuel indication system on one of its
EC135 EMS aircraft during normal operation. Following this incident, tests performed on EC135 have
revealed supply-tank fuel gauging errors on some aircraft.
The first analysis shows that the indication of the fuel quantity in the supply tanks could be
overestimated. All crews should be aware that in the worst case a red warning LOW FUEL 1/2 could
appear without any amber FUEL caution before.
The red LOW FUEL 1/2 warnings are generated by an independent switching logic with separate
sensors in each supply tank. The red LOW FUEL 1/2 warning lights continue to operate correctly
even if the fuel gauging is inaccurate.
Therefore we want to remind you that:
• After illumination of LOW FUEL warnings the procedure iaw. the Flight Manual must be strictly
complied with, notwithstanding of the fuel quantity indication.
In addition we want draw attention to the proper airmanship iaw. Air Ops NCC.OP.131 “Fuel and oil
supply — helicopters” and NCC.OP.205 “In-flight fuel management” to ensure situational awareness
concerning fuel usage and flight time left.
Furthermore, we want to remind you of Information Notice 2535-I-28 “Notes about possible water
contamination of the fuel system”.
SIN No. 2535-I-28
SUBJECT: FUEL SYSTEM
Water contamination of the Fuel System
Applicability EC135 T1, T2, T2+, P1, P2, P2+, 635 T1, 635 T2+, 635 P2+ MBB BK117 C-2
EUROCOPTER has been informed about several fuel quantity indication failures. Following the
replacement of the affected fuel probe, the indication returned to normal and the functional check of the
fuel quantity indication system has been performed successfully.
When the subject probes have been returned to EUROCOPTER for repair, the probes showed no
external damage or contamination within the two concentric metal tubes and most of the probes have
been tested, with the result, “no fault found” (NFF). To investigate the reason for these NFF’s
EUROCOPTER performed several tests to simulate the failures. As a result from these tests, the most
probable root cause is contamination of the fuel probe with water.
These tests have shown - when water is entering the space between the two concentric metal tubes of
the probe - it will decrease the output signal (frequency) of the probe. In case of a high concentration of
water, the frequency can decrease to such a level that the CAD recognizes the probe as failed –
showing either an F QTY DEGR or F QTY FAIL caution on the CAD. Also there is a potential risk that the
CAD shows a higher fuel quantity level compared to the actual fuel level within the fuel tank system.
In addition, customers have reported, when removing the defective sensor from the helicopter, that after
removing the water by the use of shop air and warming up the sensor for a certain period of time, the
sensor has been working again without any fault.
It should be noted that even for operators that regularly drain the fuel tanks, a couple drops of water
concentrated between the metal tubes of the sensor may be enough to affect the signal.
There are several possibilities for the fuel system to be contaminated with water:
· Condensation within the fuel tank system. This is mainly caused when the fuel tanks are not
completely filled and the helicopter is parked outside and/or is exposed to great changes in
temperature
· Heavy rain during refueling of the helicopter – water is entering through the filler neck
· Contaminated fuel from the source – for example fuel truck, tank, supply system or barrels
· For EC135 when performing an engine compressor wash, the water from the combustion
chamber is drained into the drain bottle. On some helicopters there is a chance that water from
the drain bottle is sucked into the engine fuel system via the Fuel Control Unit. Operating the
prime pumps prior to the next engine start will allow the water to enter the helicopter fuel system
through the fuel return line and the fuel expansion box. From the fuel tank expansion box the
water will then flow back into the RH Supply Tank.
Therefore, as explained in the AMM Task 71-65-00, 7-1, it is recommended to follow the procedure and
to disconnect the combustion chamber drain tube before prior to starting the compressor wash process.
Due to the reason mentioned above, EUROCOPTER wants to point out the importance of keeping the
fuel system free of water and other contamination. When draining the fuel system, in reference to the
documents listed below, it must be performed before the helicopter is moved, in order to allow the
maximum amount of water to be drained from the tank.
EC135
AMM, Chapter 12-30-00, 3-5
MSM, Chapter 05-25-00, 6-1
FLM, Section 4 – Preflight Check
FLM, Section 8.3 – Drainage Procedure
BK117C-2
AMM Chapter 12-30-00, 3-16
MSM, Chapter 05-25-00, 6-1
FLM, Section 4 – Preflight Check
FLM, Section 8.3 – Drainage Procedure
In addition EUROCOPTER wants to point out that water – if not drained from the fuel system – can
cause different malfunctions within the fuel and engine system.
If there is doubt that the fuel system is free of water, EUROCOPTER recommends to take a fuel sample
from the helicopter tank system and to test it for the presence of water by using commercially available
Test Strips, for example the SHELL Water Detectors or another commercially available product.
Last edited by RVDT; 16th Dec 2013 at 19:02. Reason: IN Number corrected
Purveyor of Egg Liqueur to Lucifer
If NPAS feel there is any doubt, which they obviously do to impose additional limits, then as a duty of care they should not be allowing their staff to fly them in the first place.
Thread Starter
Update statement from Bond Air Services this afternoon Monday 16 Dec:
airsound
Following our discovery during routine operations of an issue with an indicator system on one of our aircraft on the 11 December, Bond Air Services temporarily suspended service operations to allow precautionary testing. This involved detailed examinations and tests to evaluate the function and accuracy of the fuel indicator and alert system on our fleet of EC135s. Following these tests, we were able to release a number of aircraft back to full operational service immediately. Over the last few days, we have worked with the manufacturer Eurocopter to fix those aircraft which were discovered to have a fuel indication anomaly. Our EC135 aircraft are now fully operational and are available for missions with our air ambulance and police customers.
As an extra safety precaution, all our operational EC135 aircraft will now carry a minimum of 90kg of fuel at all times. We will be working with all our customers to discuss the impact of this additional precaution, and ensure we continue to meet their service needs.
Our decision to temporarily suspend service operations underlines Bond Air Services' commitment to maintaining the highest standards of safety in all our operations.
As an extra safety precaution, all our operational EC135 aircraft will now carry a minimum of 90kg of fuel at all times. We will be working with all our customers to discuss the impact of this additional precaution, and ensure we continue to meet their service needs.
Our decision to temporarily suspend service operations underlines Bond Air Services' commitment to maintaining the highest standards of safety in all our operations.
Avoid imitations
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So am I correct in reading that the fuel contents gauge and the amber contents warning light are working off the same signal input, but the red low contents warning light is independent from them?
So, if unknown water contamination has taken place, a red light alone might have been incorrectly seen as a spurious warning where the gauged fuel contents appear sufficient and the "early warning" amber light has not yet illuminated?
Yes, having read it again, I think it does mean this. Normally crew are trained to look for confirmation of a fault or caption by looking at a gauge, or vice versa. It appears that this is potentially a very hazardous thing, especially if only a few drops of water can seriously affect gauge accuracy.
So, if unknown water contamination has taken place, a red light alone might have been incorrectly seen as a spurious warning where the gauged fuel contents appear sufficient and the "early warning" amber light has not yet illuminated?
Yes, having read it again, I think it does mean this. Normally crew are trained to look for confirmation of a fault or caption by looking at a gauge, or vice versa. It appears that this is potentially a very hazardous thing, especially if only a few drops of water can seriously affect gauge accuracy.
Last edited by ShyTorque; 16th Dec 2013 at 20:04. Reason: Me grammar wasn't too good. She's better now.
Shy,
It was always drummed in to me when training on the 135 and on subsequent checks that, if the Red Low Fuel Lights came on, regardless of what the gauges read, assume the Red caption is telling the truth and land.
Interesting that Bond have decided to up the MLA to 90Kgs - so, now you have a situation where you never get to use the fuel in the supply tanks and never get to see the levels reducing so you never know whether the gauge is reading correctly or simply "stuck".
Beginning to sound to me as though the 500/1000 service ought to include a fuel system drain and re-fill to check the gauge accuracy.
It was always drummed in to me when training on the 135 and on subsequent checks that, if the Red Low Fuel Lights came on, regardless of what the gauges read, assume the Red caption is telling the truth and land.
Interesting that Bond have decided to up the MLA to 90Kgs - so, now you have a situation where you never get to use the fuel in the supply tanks and never get to see the levels reducing so you never know whether the gauge is reading correctly or simply "stuck".
Beginning to sound to me as though the 500/1000 service ought to include a fuel system drain and re-fill to check the gauge accuracy.
Avoid imitations
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Beginning to sound to me as though the 500/1000 service ought to include a fuel system drain and re-fill to check the gauge accuracy.
Thread Starter
Bond Air Services issued a further statement yesterday evening, 16 December
airsound
We note that Eurocopter has today issued a Safety Information Notice to operators of the EC135 across the world confirming that some of their aircraft have a fault in the fuel indication and alert system which means that warning system may not work properly. This was a fault discovered by Bond during normal service operations on Wednesday 11th, which we immediately reported to Eurocopter and the appropriate authorities. We understand other operators have since conducted similar tests and found similar problems with their aircraft. As soon as we discovered this issue, in line with our commitment to the highest standards of safety, we took the prudent decision to temporarily suspend service operations whilst we conducted checks on our fleet of EC135s. The results of these tests were subsequently validated by Eurocopter, and appropriate repairs made before returning the aircraft to service. We also took the decision to increase safety barriers by mandating that all our EC135s should maintain a minimum of 90kg of fuel onboard at all times.
Shy,
Water drain/sample checks are part of the Check A. Also, to answer your earlier question, yes, the Amber Fuel Caption is a function of a certain quantity of fuel or less being reached dependent of type of fuel tank but it's around the 70kg mark - the information coming from the contents sensors. The Red Low Fuel Warnings come from a different set of sensors which "detect" in a different way.
Water drain/sample checks are part of the Check A. Also, to answer your earlier question, yes, the Amber Fuel Caption is a function of a certain quantity of fuel or less being reached dependent of type of fuel tank but it's around the 70kg mark - the information coming from the contents sensors. The Red Low Fuel Warnings come from a different set of sensors which "detect" in a different way.
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EC135 Fuel Sensing Probes
An EC135 operator practices a stringent policy of checking both the bulk fuel supply and the aircraft fuel tanks for water every morning before the commencement of operations. They use the standard ‘Shell’ detecting capsules, which will detect water in aviation fuel at 30 ppm (the recommended ICAO standard).
They are fully aware of Eurocopter SIN 2535-I-28, and have been for some time.
Yet potentially serious fuel indication problems still occur with their aircraft.
At present, there is no requirement by the manufacturers Master Servicing Manual (MSM) to inspect or function check the fuel quantity indication system at 500 or 1000 hrs. The fuel sensing probes are an ‘on condition’ component (that means they are not subject to time-life or overhaul).
So, if the probes correct operation is so susceptible to water, why is there no requirement to check them at regular intervals? There is always water in aviation fuel, it may be only a couple of ppm, but it’s there. I would even go as far as to ask if the probes are fit for purpose?
The EC135 Technical Briefings from Heli-Expo 2011 (pg24) and 2012 (pg29) are of some interest.
When Eurocopter talked about a ‘worse case’ in their last SIN relating to fuel indication, they were talking about this……
Both transfer pumps off, 170 kg in main tank, 47kg in No 1 supply tank, 30 kg in No 2 supply tank. FUEL amber caution illuminated and both No 1 and No 2 FUEL LOW red warnings illuminated (I can't get the photo to paste).
If the No 1 supply quantity indication was correct, the No 1 FUEL LOW light wouldn't be on. There was actually 13 to 21 kg less fuel in the No 1 supply tank than the display was indicating. A 27 - 44% error.
They are fully aware of Eurocopter SIN 2535-I-28, and have been for some time.
Yet potentially serious fuel indication problems still occur with their aircraft.
At present, there is no requirement by the manufacturers Master Servicing Manual (MSM) to inspect or function check the fuel quantity indication system at 500 or 1000 hrs. The fuel sensing probes are an ‘on condition’ component (that means they are not subject to time-life or overhaul).
So, if the probes correct operation is so susceptible to water, why is there no requirement to check them at regular intervals? There is always water in aviation fuel, it may be only a couple of ppm, but it’s there. I would even go as far as to ask if the probes are fit for purpose?
The EC135 Technical Briefings from Heli-Expo 2011 (pg24) and 2012 (pg29) are of some interest.
When Eurocopter talked about a ‘worse case’ in their last SIN relating to fuel indication, they were talking about this……
Both transfer pumps off, 170 kg in main tank, 47kg in No 1 supply tank, 30 kg in No 2 supply tank. FUEL amber caution illuminated and both No 1 and No 2 FUEL LOW red warnings illuminated (I can't get the photo to paste).
If the No 1 supply quantity indication was correct, the No 1 FUEL LOW light wouldn't be on. There was actually 13 to 21 kg less fuel in the No 1 supply tank than the display was indicating. A 27 - 44% error.
If the No 1 supply quantity indication was correct
FUEL LOW 1 and 2 ON is the key.
FUEL LOW is FUEL LOW is FUEL LOW!
Entirely separate circuit. As pointed out in the IN.
Regardless of what the gauge indicates. Its an indication that should be backed up by fuel management policy, pilot proficiency and understanding of the systems.
Policy on FUEL LOW - RFM - Land within 8 minutes?
The scenario you quote "Doesn't look right or make sense so therefore something is wrong"
The trick is knowing what is wrong.
It is no different to a couple of other makes and models I could quote.
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Yes, it may be the key.
If a pilot knows his fuel uplift, the aircraft's average burn time and has an understanding of the aircraft's fuel system then, yes, he can second guess the indication system and know that a fuel warning MEANS that something is not right and the warning should be taken notice of...
but I'm not talking about good aviator practice, I'm talking about a system component that seems to be sensitive to a water content in fuel that is below what can be detected by commercially available testing methods.
Why should a pilot have to be suspicious of a system's integrity and have to 'second guess' it because it doesn't do what it says on the tin. It should meet the criteria of its design approval under common circumstances. If it doesn't, then it should be improved to meet those criteria and at least have a maintenance/ monitoring programme put in place in the meantime.
If a pilot knows his fuel uplift, the aircraft's average burn time and has an understanding of the aircraft's fuel system then, yes, he can second guess the indication system and know that a fuel warning MEANS that something is not right and the warning should be taken notice of...
but I'm not talking about good aviator practice, I'm talking about a system component that seems to be sensitive to a water content in fuel that is below what can be detected by commercially available testing methods.
Why should a pilot have to be suspicious of a system's integrity and have to 'second guess' it because it doesn't do what it says on the tin. It should meet the criteria of its design approval under common circumstances. If it doesn't, then it should be improved to meet those criteria and at least have a maintenance/ monitoring programme put in place in the meantime.
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Unfortunately, designers get sucked-in to incorporate the "latest technology" *
No doubt they've successfully used this measurement system for many years in industrial processing and Laboratory work.
An Aircraft is operated under somewhat more "rugged" conditions. If impurities can contaminate the fluid under measurement, to the extent the reading is wildly inaccurate, it is, IMHO, the wrong technology for that job.
float/resistance-wire and sight-glass (tube) systems are crude but robust and effective.
The pilot, however well-trained, is not normally an electronics engineer or laboratory technician. How the hell is he expected to know, memorise and understand the foibles and complexities of a "simple" fuel-gauging system which is too delicate for unmonitored field conditions.
Bloody stupid, needing to monitor the monitor
No doubt they've successfully used this measurement system for many years in industrial processing and Laboratory work.
An Aircraft is operated under somewhat more "rugged" conditions. If impurities can contaminate the fluid under measurement, to the extent the reading is wildly inaccurate, it is, IMHO, the wrong technology for that job.
float/resistance-wire and sight-glass (tube) systems are crude but robust and effective.
The pilot, however well-trained, is not normally an electronics engineer or laboratory technician. How the hell is he expected to know, memorise and understand the foibles and complexities of a "simple" fuel-gauging system which is too delicate for unmonitored field conditions.
Bloody stupid, needing to monitor the monitor
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It's not the water in the fuel (in parts per million) causing the probe to misread, it's the water pooling around the probe either causing corrosion, or as it's the lowest point in the tank, and water has a different capacitive value than fuel, causing misreading. This will happen on any capacitance type system.
If you carry out your fuel drains/checks and the same is said for your supplier then you shouldn't have this problem, which is the gist of the IN from ECD.
No doubt every pilot will claim to religiously carry out their fuel checks 100%, I call 'bull****'.
If you carry out your fuel drains/checks and the same is said for your supplier then you shouldn't have this problem, which is the gist of the IN from ECD.
No doubt every pilot will claim to religiously carry out their fuel checks 100%, I call 'bull****'.
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Cockney Steve -
Would not the "float" float on the water content thus causing the tanks to overread the amount of "fuel" available anyway regards of where the water is in relation to the fuel.
float/resistance-wire and sight-glass (tube) systems are crude but robust and effective.
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Main tank fuel
I believe that there was around 95 litres of fuel in the main tank. Even with possible faults on the supply tank warnings, why did the supply tanks not remain full from fuel transfered from the main tank. I still think there was a problem with fuel transfer.