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Thread: Troubleshooting: No power

  1. #41

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    How about battery capacity at 0F... Alternator is charging per ammeter reading during flight. I keep on battery tender when the plane sits. Almost always has a resting voltage reading of 13VDC or more. I didn't have a voltmeter on me while on this outing to see if something was amiss there but presume not since everything worked without fault after the short five minutes of flying with mediocre cabin heat. Not certain if battery or master relay but lean towards relay over battery. I don't know history of either unfortunately. I would have had to rig the hydraulic ski pump to get those into wheel mode for PAJN landing. Every time I go out I am learning something. Guess that's part of the appeal towards exploits such as the ones we choose to do around here!

  2. #42
    wireweinie's Avatar
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    Quote Originally Posted by bjh356 View Post
    How about battery capacity at 0F... Alternator is charging per ammeter reading during flight. I keep on battery tender when the plane sits. Almost always has a resting voltage reading of 13VDC or more. I didn't have a voltmeter on me while on this outing to see if something was amiss there but presume not since everything worked without fault after the short five minutes of flying with mediocre cabin heat. Not certain if battery or master relay but lean towards relay over battery. I don't know history of either unfortunately. I would have had to rig the hydraulic ski pump to get those into wheel mode for PAJN landing. Every time I go out I am learning something. Guess that's part of the appeal towards exploits such as the ones we choose to do around here!
    No backup hand pump? What would you do with an electrical failure in flight?

    The capacity of ANY battery goes down with a decrease in temperature. Until you get well below zero, the resting voltage should not be greatly affected. But as soon as you put a load on the battery (starter motor), the voltage will drop quickly. Once the engine starts, the recharge may take a little longer than normal.

    Low voltage problems that effect the relays; Extreme low volts and the relay just wont close. Not even a 'click'. Less than around 9 volts and the start relay will chatter. If this happens, just stop. If you keep trying to start the engine, the chattering will damage the relay. Also, if you have enough left in the battery to close the master relay but not crank the starter, you can still hand prop to start and let the alternator recharge the battery.

    Now for the crazy part. If the battery gets run down to a certain point you can get a situation where the start relay and/or the master relay can open (or 'drop out') as each piston comes up on top dead center due to the load on the battery. As soon as the starter motor stops turning the load on the battery is reduced and the voltage comes back up. This allows the relays to close again and the whole thing starts all over again. This is way worse than a relay just chattering as when the contacts open with 90+ amps flowing, the arcing will absolutely destroy the contacts.

    If your original description is accurate, you have a master relay issue.

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  3. #43

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    No backup hand pump. I believe hydraulic pump is same one utilized for amphibious floats for wipaire products. Not sure how one flies and pumps when pump is located under seat of co-pilot/passenger. I'm sure there is a way but I personally don't see a place where hand pump can be integrated along with a switch/lever of some sort to change flow for skis or wheels. Thoughts?

    Also while folks are engaged here, are pilots operating carb heat in winter in same manner as they do when summer flying in AK? I am curious since carb ice probability charts don't really show what happens at cold temps, I.e. Below 20F. I know really cold air doesn't hold much moisture and carb ice development requires some level of moisture in the air. During landing approaches and low throttle operations are folks applying carb heat or will that actually warm the temp up and introduce moisture in some manner? I had carb ice bite me this summer and am now analyzing all carb heat operations to ensure I am understanding it for both summer and winter ops.

  4. #44
    wireweinie's Avatar
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    This situation that you described shows that there should be a back up to the electric pump. I'm assuming you're flying a Cessna? The pump bolts to the tunnel that runs between the seats. Years ago Terry Smith showed me how he buried the pump inside the tunnel on 180/185's. A lot of work initially but an extremely clean install. The selector lever goes with the pump. It's all just some plumbing.

    This is no different than any other system on an aircraft. If it's critical for operation, there needs to be a backup that will allow for safe operation to a landing spot. Wheels down over snow or skis down over runway is NOT safe operation. But, hey, it's your acht.

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  5. #45

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    I fly a PA-18. I kind of wondered myself when I started mountain flying with skis and definitely feel more comfortable with redundancy for critiacal applications such as this. Seems like I would need to relocate the pump and if I am going that far might as well just go with the mechanical hand pump vs electrical. Let me ask this, does one have a backup to a mechanical hand pump? Do those ever have issues or fail?

  6. #46

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    My pump is located on the inside right under the false boot cowl in front of the rear right rudder pedal. The handle has a 90 degree bend and when forward just clears the door. Completely out of the way in summer I pul the handle and zip tie the handle receiver in the forward position.
    DENNY

  7. #47
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    Quote Originally Posted by bjh356 View Post
    I fly a PA-18. I kind of wondered myself when I started mountain flying with skis and definitely feel more comfortable with redundancy for critiacal applications such as this. Seems like I would need to relocate the pump and if I am going that far might as well just go with the mechanical hand pump vs electrical. Let me ask this, does one have a backup to a mechanical hand pump? Do those ever have issues or fail?
    In a Cub the hand pump is usually mounted next to your right knee. When hand pumps fail it's usually by leaking internally. Just pump faster until you can get home. If it's a mechanical failure like a pin falling out of the handle or the handle coming loose, you can use your imagination to jury rig a temp fix. With an electrical pump, you can have switch or breaker failure. Broken wires. Alternator failure or dead battery. And that's not counting the pump assembly itself. Many, many more points of failure with the electrical system.

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  8. #48
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    Quote Originally Posted by DENNY View Post
    My pump is located on the inside right under the false boot cowl in front of the rear right rudder pedal. The handle has a 90 degree bend and when forward just clears the door. Completely out of the way in summer I pul the handle and zip tie the handle receiver in the forward position.
    DENNY
    This might be something to consider. Bury the hand pump like this and leave the handle off and clipped to a handy spot. If needed, grab the handle and stick it onto the pump for use.

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  9. #49

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    All good options and viewpoints. Appreciated. I think the electrical one sticking around isn't likely. Who sells/manufactures the mechanical option?

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