Or is it?
Like I did the past four summers, this May I parked my helicopter outdoors at an ag strip — a simple runway used by crop-dusters — near the RV park where I begin my summer work season in Quincy, WA. (My first season here, in 2008, I managed to get a hangar at Quincy Airport.) My “helipad” is a concrete tie-down pad, created long ago when the ag strip was busier and was home to more airplanes.
These days, the strip is home to just one crop-duster, a yellow turbine biplane that barely fits inside a big hangar on the strip. That airplane’s predecessor was parked, partially disassembled, on the concrete pad in front of mine, tied down with frayed ropes. Its big radial engine had bled out its oil reserve years ago, leaving a grimy patch on the pavement that had absorbed dust and dirt and small pebbles throughout the years. Last year, part of its tail section was taken away. What remained was broken and forlorn, a sad reminder of what might have been a glorious past, its bright yellow paint faded and dirty from a long spell in purgatory outdoors.
Over time, birds had built nests inside its wings. They’d done this long before I arrived in 2009; I saw them come and go right from the first day I was there. Bits and pieces of straw stuck out of odd places. A bird would perch on a strut or cowling, then disappear into the airframe. I watched them while I was warming up my aircraft for a flight, or when cooling down at the conclusion of one.
The plane was still there when I arrived this May. But a few days later, I saw a flatbed trailer working near it. And then, one day, it was gone.
I hoped it was going to a new home, someplace where it would be rebuilt and would return to the sky.
Birds in the Fan Scroll
I was in Phoenix later that month, dealing with personal business, when my phone rang. It was the owner of the ag strip, Randy, who also flew the turbine crop-duster in the hangar. He’d never called me before. I didn’t even know he had my number.
“What’s up?” I asked him after we exchanged greetings.
“I’ll let Dalton explain,” he said.
I think my blood pressure must have jumped up a few points. Dalton was Randy’s ground guy. He spent a lot of time tearing around the strip on an ATV, running between the hangar and the refueling area and chemical loading area. I imagined him having some kind of mishap that involved the helicopter.
“I saw some birds flying in and out of the back of your helicopter,” Dalton told me. “When I looked in there, it looked like they were building a nest. I covered it up so they couldn’t get back in,” he finished.
Okay. A bird nest. Not something I wanted to deal with, but at least it wasn’t some sort of accident that involved the helicopter’s airframe. I thanked him for keeping an eye on things for me and for covering it up. I told him I’d be back in a few days and we hung up.
It made sense, when I thought about it. With the big biplane gone, a lot of birds were homeless. They moved to the closest replacement — my helicopter.
When I returned, I found the fan scroll cowl covered with cloth that turned out to be two old coveralls. I pulled them off to find a mess in the back end of the helicopter. Birds had flown between the fins on the fan scroll cowl (consult photo above) and had brought all kinds of hay and twigs. They’d left nesting materials inside the cowl and inside the fan itself. And there was a ton of bird poop.
What a mess!
I returned to my RV to fetch my battery powered screw driver, some hot water, and some rags. Then I got to work. First I removed the two screws holding in one of the fan cowl fins and attempted to remove all the material by reaching in. It soon became obvious that that simply wouldn’t work. So I removed the entire cowl — which involved removing about 20 screws — and began scooping out the junk I found. It took quite a while; there was an amazing quantity of the stuff. I wiped up as best as I could with the water and rags.
By then, Randy and Dalton had come by to chat. They told me to use the hose in the hangar. So I carried the filthy cowl into the hangar and cleaned it as well as I could with the hose and a brush.
When I was satisfied all the nesting material was out and the cowl was as clean as I’d get it, I put it all back together. Then I used plastic bags to cover up the fins so birds couldn’t fly back in there. That would have to protect it until I flew again.
I should mention here that I opened all the inspection doors and looked carefully throughout the interior of the cowling to make sure that was the only nest they’d built. I admit that I was surprised that they hadn’t built anything in the main inspection area, near the upper sheave, beneath the hydraulic reservoir, or under the main rotor gearbox. I tapped on the mast cowling and tailcone in an attempt to scare out any birds that might be in there. Nothing. Not any other trace of birds anywhere.
What a relief.
Flying an Aging Aircraft
I started doing a lot of flying a few days later — charter flights, mostly. I removed the plastic bags, preflighted thoroughly, and saw no other sign of birds. When I flew, everything seemed fine.
Well, I did notice that the engine seemed to run a little warmer than usual.
The cylinder head temperature gauge has a little tick mark about 2/3 from the top. In the 8 years and 1600 hours I’ve flown the helicopter, temperature in flight is usually right around this line. It might be slightly to the left (cooler) on a cool day and slightly to the right (warmer) on a hot Arizona day. I’d never seen it to the right of the line in Washington state — it simply didn’t get hot enough. Yet that spring the temperature consistently reached and edged slightly past that line.
The engine was running warm.
At the same time, I noticed that the engine was warming up a bit quicker than usual. I figure it was because outside temperatures were pretty warm. That would also explain why it took a bit longer to cool down.
I also noticed a slight decrease in performance — I simply couldn’t maintain the 110 knots cruise speed I’d usually gotten when flying light. That could have something to do with the accumulation of dust and bird poop on the top of the main rotor blades. I cleared it off as best as I could as often as I could. I also figured that the performance issues might have something to do with engine compression; I’d learn more at its next 100 hour inspection.
Hell, my helicopter was getting old. Little changes like this were bound to happen.
Overall, however, the helicopter ran smoothly without any problems. I did numerous charter flights and numerous cherry drying flights without any problems whatsoever.
I did also notice some fresh bird poop on the fan scroll cowling, but regular examination of the area failed to show any trace of bird habitation. I figured that the birds just liked perching and pooping there with their old biplane home gone.
I should have known better.
The 50-Hour Inspection
I dried 73 acres of cherry trees yesterday morning. Afterwards, I landed at Wenatchee Airport, waiting for more expected weather to move in. I had just 2 hours left on my Hobbs meter before I’d need a 50-hour inspection. A 50-hour consists of an oil change with a filter change plus the removal of the spark plugs for inspection and cleaning.
When it became obvious that weather wasn’t moving in anytime soon, I figured I’d get the 50-hour inspection taken care of while I was there; more rain was expected the next day and I didn’t want to overrun the inspection time. I ran up the engine and repositioned the helicopter in front of Alpine Aviation’s hangar. While I was driving down into Wenatchee to fetch a case of oil, the excellent mechanics there would drain the helicopter’s oil and start working on the plugs.
I was gone about 45 minutes. (I admit I also stopped at Dairy Queen for a chocolate shake.) When I returned with the oil, I saw a bird nest, complete with pale blue eggs, on the floor in the hangar.
I put the case of oil down and looked up at the ceiling. “Did this blow off the roof or something?” I asked Mike, who was working nearby.
“No,” he replied. “Cass pulled that out of your helicopter.”
I stared at him. “You’re kidding.”
But Mike wasn’t kidding. “He’s got quite a mess to clean up.”
I went outside to take a look. The left side panel was off and the panel that normally hid the top half of the engine was also off. Cass was pulling bits and pieces of straw off the engine’s cooling fins.
“I got a picture of it,” he told me. On his phone, he showed me a photo of the engine with hay stuffed into the area on top of it.
“Both sides?” I asked.
“Mostly this side,” he assured me. “But it’s in the oil cooler, too.”
He spent an extra half hour with a shop vac and compressed air, cleaning the nest out of the engine compartment. Mike waited until he’d gotten most of it out before pulling the plugs on that side.
As you might imagine, I was troubled by this. A preflight inspection should find problems like this. But mine hadn’t. The nest had obviously been in there for some time — perhaps a month or more. It was probably causing the warm operating temperatures I’d noticed. (With luck) it could be causing the dip in performance, too.
Fortunately, it hadn’t caused a fire.
I talked to Cass about it. He assured me that there was no way I would have spotted it on a preflight. He had to remove two panels — both of which were secured with screwdrivers — to see the nest. This is not something that’s done on any kind of standard preflight inspection. And since the temperature and performance issues I’d noticed were not substantial, there was no reason to go beyond a standard preflight inspection.
A few lessons can be learned from this experience:
- If an aircraft is left outdoors, in an area known for bird nesting activity, a preflight inspection should include a search for any bird activity at all. Poop is a good indication of bird activity.
- If an aircraft you’ve been flying for years suddenly shows any change in gauge readings or performance, it could indicate an issue that needs to be found. Look beyond a preflight inspection; think about what could have changed since you noticed the different readings.
- A preflight inspection cannot uncover all problems with an aircraft. It’s limited by what you have access to when you make the inspection.
Knowing all this, would I do anything different? Yes. The next time I see a change in the helicopter’s gauges or performance, I’ll follow up with a mechanic. I may have been lucky this time; I might not be so lucky next time.