Electrical Wiring Continued

The new Rotorway Talon models have a completely new electrical system and this discussion does not apply to them.

Below is a photo of the fuel pump inertia switch bracket that shows where the alternator wire rubbed and then shorted out. The wire in the photo has been soldered together and shrink wrap was later applied. Then the entire wire bundle was re-routed and properly secured- see the photos below. This short took out all of the components at altitude and resulted in a full down autorotation for real. This was caused by the builder improperly routing and protecting his wiring harness and a potential problem with the overhead wiring if a short circuit occurs.

If the alternator wire is allowed to short out the power supply fuses in the overhead panel can all blow shutting off power to the engine systems.

In the below photo I was flying with a student when the engine on his Rotorway 162F quit and the FADEC display went blank. The wire bundle had run along the frame and when the improperly constructed fuel tank strap slid down the frame the bracket cut into the alternator wire and the wire shorted. We were able to auto to the ground safely with no damage and you can see how the wiring is now properly supported and stood off the frame while being protected by plastic spiral wrap.

 

Look closely at the bottom of the fuel tank bracket where it is sitting on the frame. You can see the carbon still there from where it cut into the wiring harness and shorted out all of the engine support systems causing a complete engine failure. The photo was taken after we had re-routed the wires, protected the bundle in spiral wrap, and used soft plastic hose as stand-off supports.

 

The photo below I am holding the wire where the rear Fuel tank bracket cut into the alternator wire bundle and caused the short.

In the photo below you can see where we put the fuel tank back into it's proper position as discussed in the fuel tank strap section of Hints and Tips. We have also re-routed all wiring away from anything that can cause a short, protected it with plastic spiral wrap, and made soft plastic hose stand-offs to support the bundle off the frame.

The photo below shows how we re-routed the repaired wire bundle and supported it. It is also protected by plastic spiral wrap. Notice the rubber protector for the wires as they enter the over head panel box. The sharp edges of the fiberglass hole will cut right though any unprotected wiring.

On my own early Rotorway Exec 152 I installed an oil cooler with a cooling fan and a switch to activate it. Above the switch is a small green light that indicated that the fan was on. All indicator lights except the red warning lights might benefit from being on a dimmer for night flying. Every switch had it's own circuit breaker. Notice I even had an alternator warning and oil pressure warning light, good things to have. Warning lights get your attention should a failure occur. Your helicopter might benefit from an ALTERNATOR WARNING LIGHT. If the alternator fails or the water pump belt breaks you need the warning to allow sufficient time to safely reach the ground before the engine quits. If it illuminates, enter an auto, monitor your engine condition, and if you have the power, initiate a power recovery at the bottom of the auto.

I have copied an advertisement for a nice alternator warning light below.

The add reads:

"The Very Best “13 Volt Idiot Light” Since Hector was a Pup!
US$39.95 This is the cheapest insurance you can buy. Don't fly without proper warning lights. How much is your ship and your life worth???

They call these “Idiot Lights”. An “Idiot” is defined as an epithet that can be directed at anyone but you. So do this for your friends—they really need it.

Since your alternator and battery voltage is about 14.5 volts when the alternator is working, a Low Voltage circuit trips at 13 volts to tell you that your alternator has failed—and from that point you’re going to be losing electrical energy—so you’d better start making plans if you need the electrical power. The FADEC computers cut out at somewhere over 10 volts so you need a warning indicator

http://www.periheliondesign.com/moreproducts.htm"

This light will also tell you if your water pump/alternator belt breaks. If it illuminates you can look at both your voltage gauge and your water temp gauge to determine the cause as you locate an emergency landing spot on the ground. If it is a belt break, the water temp will begin to rise and an emergency descent will be necessary to save your engine. An alternator warning light is a super investment and should be on every Rotorway helicopter.

Note that the new Rotorway Talon uses an electric water pump so it no longer requires the water pump belt.

 

 
If you want your Helicopter battery to last CLICK HERE
If you would like to learn how to make a simple wire standoff CLICK HERE