Geoff13 Posted July 6, 2015 Author Posted July 6, 2015 Geoff , well done on getting to the ground safely, But a couple of questions spring to mind.......................... 1. How was is that an electrical dead short occurred? and 2 . What was the fuse (main or pump) doing while your aeroplane was catching fire? ....Just wondering Both very good questions. I have asked several times of several people. To date I have not been given a satisfactory excuse. 1. The wiring diagram once sourced from the factory as it was not in the POH shows that the pump should be fused with a 5 amp fuse. It wasn't. 2. The main fuse is 30 amps and the pump was rated to 5 amps so I assume that the pump would be able to burn out without taking out the main breaker. 3. The pump had been on but was turned of a minute or so before the smoke started. 4. I assume that the pump either seized or shorted out, causing the switch to short circuit and in the absence of a suitable fuse generate enough heat to melt the metal case of the pump thus allowing the smoke out. Oh one more thing, it is amazing how much smoke came out of that little box.
Oscar Posted July 6, 2015 Posted July 6, 2015 Geoff: following your information, I have partially dissected the old Facet 'brick' style pump from my Jab. for research. Whether the information I have so far gained applies to the modern ones, I cannot say, but it may well be that the design hasn't changed much. In the older, points-style 'Gold Top' designs - which have a pretty good reputation - the points are in a sealed, argon-filled enclosure. In the 'brick'-type, the entire assembly is potted in some sort of foam - which (if that was the pump in your aircraft) was quite possibly the source of the smoke - and you and your wife may well count yourselves lucky for just minor health consequences. Some foams generate cyanide as a product of combustion, or so I believe. Your mention of the POH defining a 5-amp fuse, suggests a Facet 'brick' style pump. From my investigation so far, it appears that the bottom plate of those acts as a heat-sink for the controlling electronics ( probably a transistor/switching electronic 'brick' module); the designers quite possibly thought only that it would be mounted to a steel / metal substrate, so (in the case of Jabs. at least) mounting it hard onto a 'glass matrix would not afford any additional heat dissipation. Possibly worth noting, for Jab owners (and any owners of 'glass aircraft where the boost pump is mounted to the aircraft frame without stand-offs). Finally - and I have to ask this: do I read between the lines, that Foxbats come standard with pvc-insulated wiring rather than aircraft-grade teflon sheathed wiring? It appears from your posts that you have recognised the risks involved in flying anything using pvc-insulated wiring. I share that concern.
Geoff13 Posted July 6, 2015 Author Posted July 6, 2015 Oscar thank you I did post a photo of the pump in the last post. Foxbats do come with Teflon wiring, however the Aux Fuel pump was and added option, and appears to have not been fitted to Foxbats own standards. (I could take some guesses about that but not on a public forum). The wire to the pump was as previously stated Teflon down to the last 6-10 inch tail which was automotive. That is not common either. From what I can see the other accessories are Teflon to the end.
Oscar Posted July 6, 2015 Posted July 6, 2015 Geoff - thanks, I had not viewed the piccy! Yep, a Facet brick type and this is - I suggest - seriously important information for a lot of Recreational aviators, as this is probably the most common pump installed. Exactly the pump I have intended to use. Those do not allow for substitution of Teflon wiring for the pvc wiring they are assembled with - they are sealed. The fact that there could be an electrical short between the electronics and the casing, is a serious issue for installation. I am in NO way an expert on electrics - not even an advanced Bush Mechanic - but my Sparky friend who IS will be conducting a forensic examination of our old Facet brick pump shortly, and I'll report back. My first reaction is - that the pump case should be also earthed to the power supply, so if there is an issue with the internal electronics, the fuse (that SHOULD have been there) will blow before the pump casing is napalmed..
gandalph Posted July 6, 2015 Posted July 6, 2015 Geoff, First of all let me mirror all the others that have congratulated you on you handling of what was a serious in flight emergency. I reckon you did a great job! You got your wife and yourself safely back on the ground. How could there be a better outcome than that? Can I ask if you plan to replace the master switch? If it was the wires in the pump arcing that caused the hole to be burnt in the steel casing I'd be a bit concerned about the integrity of the switch after handling (and switching) that amperage. I'd also be going over all the electrical joints and connection in the circuit with a good magnifier and strong light looking for signs of hot joints. And finally I'd be taking the damaged pump and a large jar of vaseline with me when I went to talk to the person who installed the pump. 2
Geoff13 Posted July 6, 2015 Author Posted July 6, 2015 Geoff, First of all let me mirror all the others that have congratulated you on you handling of what was a serious in flight emergency. I reckon you did a great job! You got your wife and yourself safely back on the ground. How could there be a better outcome than that?Can I ask if you plan to replace the master switch? If it was the wires in the pump arcing that caused the hole to be burnt in the steel casing I'd be a bit concerned about the integrity of the switch after handling (and switching) that amperage. I'd also be going over all the electrical joints and connection in the circuit with a good magnifier and strong light looking for signs of hot joints. And finally I'd be taking the damaged pump and a large jar of vaseline with me when I went to talk to the person who installed the pump. Gandalph with approval from the factory the pump and wiring was removed. I believe that the factory have stated no more pumps to be fitted until this is sorted. Probably a good idea to inspect other wiring that would have been in the unprotected circuit and I will suggest that to the L2 who maintains the aircraft. I certainly understand about taking the pump with me when I find out who fitted it, and I am getting closer to that. However I disagree about the vaseline. I was thinking of a blow torch to heat it up with just so he can get the feel of the heat. Using Vaseline would simply be to easy. 3 1
gandalph Posted July 6, 2015 Posted July 6, 2015 Yeah, you're right about the vaseline. What was I thinking!
Nightmare Posted July 6, 2015 Posted July 6, 2015 Hey, you put the plane down safely with no injury or damage to plane or property, then you had the problem fixed and flew it home again.... what more can a pilot do? No criticism here. Your wife is in no better hands IMHO, hope she gets the courage to fly with you again. Tony. 1
Aldo Posted July 6, 2015 Posted July 6, 2015 I have wondered long and hard about making this post Geoff In my opinion the outcome is a direct result of your currency, competence and the training you received which obviously you have put to very good practice. The question of whether you panic or not is something any one can answer until it happens to them. Very well done, hopefully your wife will get back up in the air with you again, don't push her though. My wife learnt to fly initially because she figured if she was to be a passenger she may as well be able to land if something happened to me. Something like a TIF may be the go. Aldo 1
SilverWing Posted July 10, 2015 Posted July 10, 2015 My sympathies lie with Geoff and Julie - while I have been aware of the incident from immediately after it happened, Geoff's recounting really brings home what it is like to face such a potentially life-threatening in-flight emergency. I am full of admiration for his cool head; if anything like this ever happens to me, I hope I can respond in a similar way. I also hope Julie, his wife, will soon be able to get back in the air, as this was an incredibly rare incident. As several people have commented, Geoff is probably one of the safest pilots around and one with real-life emergency experience to his credit. All factory built Foxbats have aircraft grade wiring. In the case of the Facet 'solid-state' fuel pump, the last few centimetres of wiring are automotive grade wire, which is impossible to change without damaging the sealed pump. The factory wiring diagram clearly shows that the pump should have been wired through the spade-style fuse board. They are investigating how it could have happened that it was not. It is also curious that the smoke developed after the pump was switched off and so far, investigations have not confirmed for certain how this could happen. The Aeroprakt factory has always advised against the use of auxiliary electric pumps, arguing that they are not necessary in the Foxbat, where the gravity flow is plenty to keep the engine running. So far as I know, this aircraft is the only one in Australia to have had an auxiliary pump fitted and only one of a very small handful world-wide. At the present time, the factory will not carry out or approve further installations of auxiliary electric pumps until they are completely satisfied as to their safety and reliability. Thank you, Geoff for your candid and objective report which has lessons for all of us. 1 2 1
jetjr Posted July 10, 2015 Posted July 10, 2015 Just thinking, seems like wiring issue to me the only way this can occur is if switch (and maybe fuse too) is on Negative side of circuit, and some internal bridge to ground If switched on positive side this couldnt happen. Grounding case to neg wire wont change anything It is faintly possible switch fused on, but the pump would keep running and/or should blow even 30A fuse Id have thought
Oscar Posted July 10, 2015 Posted July 10, 2015 From initial dissection and examination of my old Facet 'brick' pump, the hole shown in Geoff's picture is actually already drilled through the casing and hidden behind the label. It looks to me as if it is the injection point for the foam encapsulation for the pump interior, and if my (inexpert) assessment is correct, it was not arcing between the electronics and the case but simply overheating of the foam to the point where it caught fire. That should never have happened in a proper fused installation; IMHO a defect report and the removal of the licence for the installer is seriously indicated. In respect of not installing a boost pump: the function of a boost pump is primarily to provide a redundant fuel delivery system in the case of failure of the mechanical fuel pump and secondarily to ensure that vapour lock does not occur. Has the Foxbat fuel delivery system been tested at the FAA-mandated 110F fuel temp, for a full-power climb to service ceiling?
Guest Maj Millard Posted July 10, 2015 Posted July 10, 2015 My sympathies lie with Geoff and Julie - while I have been aware of the incident from immediately after it happened, Geoff's recounting really brings home what it is like to face such a potentially life-threatening in-flight emergency. I am full of admiration for his cool head; if anything like this ever happens to me, I hope I can respond in a similar way. I also hope Julie, his wife, will soon be able to get back in the air, as this was an incredibly rare incident. As several people have commented, Geoff is probably one of the safest pilots around and one with real-life emergency experience to his credit.All factory built Foxbats have aircraft grade wiring. In the case of the Facet 'solid-state' fuel pump, the last few centimetres of wiring are automotive grade wire, which is impossible to change without damaging the sealed pump. The factory wiring diagram clearly shows that the pump should have been wired through the spade-style fuse board. They are investigating how it could have happened that it was not. It is also curious that the smoke developed after the pump was switched off and so far, investigations have not confirmed for certain how this could happen. The Aeroprakt factory has always advised against the use of auxiliary electric pumps, arguing that they are not necessary in the Foxbat, where the gravity flow is plenty to keep the engine running. So far as I know, this aircraft is the only one in Australia to have had an auxiliary pump fitted and only one of a very small handful world-wide. At the present time, the factory will not carry out or approve further installations of auxiliary electric pumps until they are completely satisfied as to their safety and reliability. Thank you, Geoff for your candid and objective report which has lessons for all of us. So as the Australian importer who do you think fitted this one against factory recommendations ? .....had this outcome been not as well handled, RAAus investigators would certainly want to know right now..
gandalph Posted July 10, 2015 Posted July 10, 2015 Ross, why wouldn't the RAA investigators still want or need to know why the pump was fitted; how the pump was fitted and who signed the installation off? The fact that Geoff and his wife escaped unharmed (physically) from this near calamity is no reason for the RAA to shrug off an investigation. 1 4
facthunter Posted July 10, 2015 Posted July 10, 2015 Oscar gives two reasons why it might be a good thing to fit a pump. Mogas can have vapour problems. Might not happen in colder climates, and there's the back up factor. A fuse protects the wiring.. It's rating should be appropriate to the current the wiring can take. If a pump was faulty and had say bearing failure the fuse won't protect it till the current goes way above normal, and causes it to pop if it's a Circuit breaker, or melt if a fuse. It won"t necessarily guarantee protection against fire or smoke if it heats up slowly. Nev 1
SilverWing Posted July 10, 2015 Posted July 10, 2015 So as the Australian importer who do you think fitted this one against factory recommendations ?.....had this outcome been not as well handled, RAAus investigators would certainly want to know right now.. The pump was fitted by the factory. At the time it was fitted during manufacture - over two and a half years ago - they would agree to do so if the customer demanded. Their suspension of the pump as an (unlisted) option or approval of local installations was only announced following this problem. 1
Guest Maj Millard Posted July 10, 2015 Posted July 10, 2015 The pump was fitted by the factory. At the time it was fitted during manufacture - over two and a half years ago - they would agree to do so if the customer demanded. Their suspension of the pump as an (unlisted) option or approval of local installations was only announced following this problem. Thank you.....do we know if the failure was in the pump itself or from an incorrect installation ?....there are a lot of us using those pumps out there.
Oscar Posted July 10, 2015 Posted July 10, 2015 The pump was fitted by the factory. At the time it was fitted during manufacture - over two and a half years ago - they would agree to do so if the customer demanded. Their suspension of the pump as an (unlisted) option or approval of local installations was only announced following this problem. That is, by anybody's estimation, a MASSIVE failure to deliver a product fit for purpose. I would place it as culpable negligence and if Geoff had not been as good a pilot as he was when faced with the situation, Aeroprakt would have been the recipient of a major lawsuit. Still should be. 1
facthunter Posted July 10, 2015 Posted July 10, 2015 Sure Oscar, but if many of those pumps are fitted ,( as Maj suggests) we have a general problem, out there. For the level of the risk the Foxbat is just another aeroplane. It's NOT unusual to fit a fuel pump. They run full time on an injector system and at higher pressures. Nev 2 1
Teckair Posted July 10, 2015 Posted July 10, 2015 And finally I'd be taking the damaged pump and a large jar of vaseline with me when I went to talk to the person who installed the pump. I wouldn't bother with the vaseline.
jakej Posted July 10, 2015 Posted July 10, 2015 Hey peoples, maybe we should be looking at the big picture here. Geoff13 did a greatr job BUT he should not have been put in that position due to what may have been a bad design or installation IMO. Methinks toooo... much emphasise on the pump, they are everywhere & have been used for a long time, .... just saying, not defending. The "problem" , in the first instance, appears to be a lack of circuit protection (fuse/breaker) rather than the pump or wiring type. Normally when you have a short circuit (say pump sieze) then the extra 'load' would/should blow the fuse/breaker. With tefzel wire, not automotive type, there is no This then raises the issue of some (maybe one) manufacturer NOT having a Battery master switch/solenoid (within 6" or) of the battery. Why do we have fuel taps ?- to either change tanks OR turn off fuel. Then why doesn't some aircraft have a battery master ( ie a tap) ? - maybe it's penny pinching & not about you or passenger safety. There are only 2 sources things that can feed a FIRE in your aircraft - Fuel or Battery - we need to be able to turn off BOTH. Jake J 3
turboplanner Posted July 10, 2015 Posted July 10, 2015 You won't get vapour problems with gravity feed though FH - it's like a permanently running pump. 1
Oscar Posted July 10, 2015 Posted July 10, 2015 Sure Oscar, but if many of those pumps are fitted ,( as Maj suggests) we have a general problem, out there. For the level of the risk the Foxbat is just another aeroplane. It's NOT unusual to fit a fuel pump. They run full time on an injector system and at higher pressures. Nev Probably all Jabs. - just for a start! But - has anyone ever heard of a Jab boost pump catching fire? - and Jab themselves state ( or used to) that simply leaving the boost pump on, is acceptable practice. (I doubt if many people ever did that with the standard Jab alternator) The 'brick' type Facet pumps are cheap and cheerful by comparison to even the Facet Gold Top pumps, but - mostly - they work reliably. By cost comparison with TSO'd boost pumps - (e.g. the Weldon PMA'd pumps) the Facet is 1/10th the price - and that's for entry-level TSO'd pumps. Conscionable installation would have included recognisance of the fuse requirements. 1
Oscar Posted July 10, 2015 Posted July 10, 2015 You won't get vapour problems with gravity feed though FH - it's like a permanently running pump. WRONG, if there is a low point in the line between the tank and the carburettor in any angle of flight.
Guest Maj Millard Posted July 10, 2015 Posted July 10, 2015 The high wing Lightwing didn't come out of the factory with an electrical boost pump, however one is shown as an option in the electrical circuit. Fuel flows just fine with gravity from both tanks, and both are always selected for takeoff and landing. I have fitted a facet pump however, the lowest pressure one I could find, ( refer Facet pump web site) in series in the main supply fuel line as a backup to the engine pump should it ever fail. You must respect the upper pressure limit of the Bing carbs so you do not need a high pressure pump. I also have a fuel pressure gauge on the panel (at left of panel) which I believe to be one of the most valuable gauges in any aircraft. I only occasionally use the elect boost pump for takeoff or landing and mainly operate it for about 3-4 seconds prior to starting to put some fresh fuel into the carb bowls. It brings the fuel pressure on the gauge just up to the bottom of the green or about 2psi. If I ever have a failure of the engine pump and I'm in the boonies out west somewhere, hopefully the electric boost pump will keep things flowing and take me to a safer place.
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