September 17, 2013 at 11:50 am #84465
I have a FIKI ’78 C340A (Ram VI) with BF Goodrich aftermarket boots and I have a curious problem that I originally thought was temperature related and that is I am unable to pop the boots up high. They work great down low and got quite a workout yesterday. However, up high, usually above about 15-17K, they will not inflate. Actuation of the system results in the typical drop in vacuum which means that the valve must be actuating but it remains actuated, the vacuum remains low, and the boots do not inflate. I have to manually disable the sequence with the switch otherwise the system vacuum remains low.
I would have thought that the valve shuttle was simply hanging up at low temperatures but that does not explain why I have low vacuum.
Any thoughts? Thanks in advance!September 17, 2013 at 2:10 pm #100679cochraneParticipant
The fact that you have to manually intervene to discontinue the cycle suggests that the sequence timers are not working properly. After ~ 12 seconds the deice system should automatically shut down, irrespective of boot inflation status. The stabilizer boots should activate for 6 seconds, close, then the wing boots should activate for 6 seconds. When you are above 15,000′ does the stabilizer boot inflate then deflate within the 6 second interval?September 17, 2013 at 6:36 pm #100680
One would think that if the problem was with the timers it would not occur specifically above a certain altitude (or below a certain temperature). If the system requires that an inflation pressure to be maintained for a period of time before deflation then this could explain why the cycle must be manually reset. On my system the tail and the wings inflate simultaneously, per the design.September 17, 2013 at 8:47 pm #100681cochraneParticipantquote RPinkowski1:
Agreed, there should be no altitude dependence with the timer. But if the timer outputs remain on after 12 seconds you might want to take a look.quote RPinkowski1:
The system does not use pressure feedback coupled with time to determine when to switch the valves / deflate the boots – it is strictly based on time.quote RPinkowski1:
If you have a FIKI 1978 340A and the serial number is greater than 200, the tail should inflate for 6 seconds followed by the boots inflating for 6 seconds . The description you provided is how the early, non-FIKI 340’s design was implemented. If both sets of boots (tail and wing) are inflating simultaneously there is a problem.October 13, 2013 at 12:02 am #101053
I think you have the same problem that I had. Moisture in the valves from leaky boots. Need to clean all valves and then pressure test boots. Patch all the leaks and then the system will work. I chased this same problem too long and it was a non obvious leaks in the boot.October 13, 2013 at 12:12 am #101057quote RPinkowski1:
I just got through troubleshooting this same problem. We also thought of moisture in the lines as the boots would not inflate when the temperature was below -1C OAT (typically above 15K this time of year). In short, the symptoms were the same as what you are experiencing. I don’t think it is a problem with leaky boots since they inflate in the lower altitudes (warmer temperature) and there is no reason why they would not inflate at higher altitudes (colder OAT). In my case, I suspected the valve was freezing up and that is in fact what was happening. The reason why it was freezing up was a little bit more elusive.
Juan Oviedo (DFWAM) cleaned the main valve with Sonic cleaner but it seemed fine. They then ran a pressurization check and found a slight leak in the pressurization hoses that would direct warm moist air coming out from the cabin on to the valve which would then freeze it up. Fixed the leak, fixed the problem. See the photographs below. I suggest you first check for moisture in the main valve. If this doesn’t work, see if you have a leak in these same hoses. Interesting thing is the pressurization system held good differential in flight.
Good luck.October 14, 2013 at 5:16 am #101072
I had a similar issue. Weak/no inflation at altitude. Turns out one of the solenoids had a broken wire. Hence only one was working. Fixed the wire and it works like a champ. Whether it’s freezing up or there is a broken wire I say one of the solenoids is not working.October 29, 2013 at 6:49 pm #101315
Thanks everyone for the feedback, I believe that I have finally rectified the issue and thought I would pass along what we did.
I have an aftermarket BF Goodrich system which utilizes three valves. I suspected that one of the three were hanging up with the colder temperatures in the flight levels. I first replaced the one in the nose bay as I thought that anything in the nacelles would stay at least somewhat warm. This did nothing.
I then replaced just one of the valves in the engine nacelles and this seems to have rectified the problem. Four flights now at or above 15K and was at FL230 last night, all works well.
I think I can feel comfortable that the problem is fixed, wasn’t cheap but now everything works; just in time for icing season.October 30, 2013 at 2:28 am #101325rwelshParticipantquote :
Where in the 340 was that picture taken of the soap bubbles? Is that up in the lower nose bay? I didn’t know there was a deice valve in the nose.October 30, 2013 at 4:27 pm #101336quote RWELSH:
There is one with the BFGoodrich system.
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