A thread on VR this week about the alternator light is another example of why I’m doing this. In the R22 POH, the alternator light emergency procedure gets just a paragraph and is pretty straightforward: alternator switch off, non-essential equipment off, alternator switch on. Land as soon as practical if the light remains illuminated.
The thread on the forums this week started with a cracked drive belt, but moved into a discussion about the mechanical reasons the alternator light might become illuminated the grief that could cause you. In the POH, the primary concern is loss of electrical power, which would cause a failure of the governor and tachometer, and no way of regulating your MR RPMs. Even without an alternator, the battery should have 10-15 minutes of reserve power, allowing you to follow the procedure for landing as soon as practical (go to the nearest airport where repairs can be made). What isn’t in the POH is the risk of a loose alternator belt flying around the engine compartment. Once freed from the pulleys, it can become entangled in the drive belts, leading to their failure and an emergency autorotation. This is exactly what happened in a September 2007 accident. In this case, the first indication of a problem was the sound of the alternator belt breaking, followed by RPM instability. However, one of the posts on the VR thread suggested a scenario where an alternator light could indicate a failing alternator or alternator bearing, leading to failure of the belt itself. Even if the drive belts aren’t damaged, the belt that came loose in the 2007 accident contacted the oil cooler and lines. Conclusion? Consider making an emergency landing if the alternator light illuminates, and figure the problem out on the ground rather than in the air.
The other thread that was really interesting was about a pilot who failed his commercial ride. Basically, his instructor filled the tanks on the helicopter while the pilot was doing his ground portion of the check ride. He didn’t recalculate the W&B for the actual fuel load, and ended up 16 lbs over MGW. Shitty way to learn a lesson, but props to this guy for posting is story. I wonder if there’s an inherent complacency toward fuel because we do it so casually for our cars (except in Oregon and New Jersey!). Planning your fuel load is the first important step, but what got the pilot on his check ride was confirming what went in. Where I trained, we did the fueling ourselves, but I’ve been to plenty of airports where you touch down to refuel, and a truck comes bounding over to you. These guys aren’t going to attach the same importance you are of putting on exactly what you tell them. This job would be easier if you could always trust your fuel gauges or had a dipstick for exactly determining your fuel load. If you have the R22 weight and balance calculator and a smart phone with an Excel application (like Grid Magic), you can recalculate your fuel load right after you finish fueling.
A bigger problem that I’ve seen is not testing fuel for water or debris. Flying out of the same airport, you get to trusting your fuel source. Out in the real world–where you’re going to be flying from different locations, maybe getting fuel from barrels cached in the woods of North BFE–having a well entrained habit of always checking your sump might be a good idea. Since I learned to fly airplanes at an airport with a fuel service, I got into that habit. But another good reason is that things change, and you don’t always realize the implications. While working on my instrument rating, I started seeing rust particles popping up in the sump. This was after months of not having any indication of a problem. Turns out, the pump on the fuel truck was switched out while the original was being serviced, and that was the source.
Here’s another good one. Before you pulled the helicopter out of the hanger this morning, you checked the sumps and it looked good. It’s 10 degrees C outside and snowed last night, so you’re happy this will be a quick refuel–just 3 gallons. You drive the fuel truck from the tank out to the ramp, pick up the nozzle, pop it in the tank, and get your fuel. You know the truck is topped off every night, and you’ve never had debris or water come out of this tank. So, is there a good reason to check the sumps again? Anybody make a guess. Bueller? Bueller?