Last weekend I took my longest straight-line flight to date with the Swift I now own. I logged roughly 1.5 hours each way and got to know the plane a little better. It definitely makes different sounds than my previous Swift. That is a function of the larger engine (Continental O-300 then vs. Continental IO-360 now) and a major difference in propellers ( Fixed pitch Sensenich then vs. McCauley 3-bladed constant-speed now). The engine sounds much more powerful and the wind noise pulses are much different with the 3-bladed prop.
The flight was made to attend a Swift lunch date. The Northern California Swift group sets a date each month to meet somewhere for lunch. In the past the attendance has been great, but in recent years it has dropped off for some reason. I would imagine that it’s a combination of age, retirement budgets and fuel costs – the group isn’t getting any younger and although the Swift seems to have a cult following the younger pilot crowd seems to be drawn to the high-tech shiny new planes over the proven classics.
I had a really good time visiting with the other Swift club members who attended the lunch gathering. As we were leaving a group of five RVs landed and parked near our spot – probably taking advantage of the same restaurant we had used. As I made my way first to the fuel island and then the end of the runway a Curtiss P-40 took off, made a low pass or two and then landed. He taxied right by me on the way back to his hangar as I accomplished my magneto check at the end of the runway. Nice performance.
After that flight the Swift sat for 4 days while we hosted a house guest. When I finally got back to the hangar I opened the door and found a new liquid on the floor.
Preflight inspections of aircraft should always begin as you walk up to the plane. Does the ‘big picture’ of the airplane look right? Is there anything parked or placed near the plane that will affect moving the plane from its parking spot? Is the area behind the plane clear? Is there anything under the plane that indicates something has leaked from where it should have been contained?
Hmmm. A new spot of red fluid under the nose – not just the nose, but out front – under the propeller. No chance that it’s hydraulic fluid – there’s nothing that far out front that uses that type of hydraulics. However, some constant-speed props have a hub filled with lubricating oil that has been dyed red – and mine is one of them. The manufacturers started doing that to allow easier identification of cracked propeller hubs. More investigation was needed.
Removal of the spinner provided a closer look. No leaks were obvious anywhere on the hub, but a few drops of red oil were found on the spinner backing plate. A closer look at the inside of the spinner showed an area of red fluid splatter around one of the propeller blade openings.
I bought this plane from an estate around five years ago. The prop had been purchased new from McCauley and installed on the plane by the previous owner who then flew it for about 75 hours before he passed away. The family let the plane sit for about 5 more years without flying it before they decided to sell. I bought it and took another 5 years to get it in flyable condition as I worked between airline trips. Letting any piece of mechanical equipment sit without using it or taking any preservative action is the worst thing you can do. I had to rebuild most of the systems on the plane – especially anything that had a rubber seal in it.
I had been planning to send the prop out to a shop for inspection, hoping to have it done over the winter months when I wouldn’t be flying much anyway. This event has moved up the schedule to now. I called a couple of different shops in my general area and asked each a bunch of questions.
- What would you recommend in this particular case?
- What services would you provide?
- How much will this cost?
- Is pick-up and delivery included?
- What is the time involved for getting it all done?
I decided on a shop in Northern California based upon all the work that they will do for a reasonable price. As an added benefit, they are an authorized McCauley Service Center. I had also used them to overhaul my Sensenich fixed-pitch prop on the other Swift, so I had a history working with them that had been positive.
Unfortunately they can’t pick up the prop for another week and will have it for a week before they deliver it back to my hangar. Guess I’ll have time to polish the bottom of the plane and get some work done in the cockpit area – making some pockets in the side panels for charts and checklists and installing an aux. power receptacle for a future ‘authorized electronic device.”
I’ll let you know how it all works out.
3 responses to “Not Flying for a While”
Another good post, Tracy and an important lesson as well. There is dye in that oil for a reason! While the tiny amount noticed when away from home was not critical, it certainly needed a thorough investigation. Said investigation has led to some job security for the prop maintence folks and additional flying comfort for you – at a price. As expensive as maintenance can be, it IS part of the ownership load. At least you are able to do most of it on your own (A&P and I recall?). Always better to fix now and not have to worry about it. I sdon’t own an airplane, but Cedarglen’s ‘kit’ includes multiple machines, from gas-driven pumps to weed-eaters and chain saws to a 4-cyl chipper. All get walk-around inspections and prescribed maintenance. I’ve yet to have an in-service failure and I think I know why… You’re on to something good and the message is clear. Thanks for the reminder. -Craig
So how does the CS Prop work with sealed oil in the hub? Does it pressure up the prop shaft and press against the oil in the hub with a diaphragm arrangement?
The oil sealed in the hub is strictly for lubrication. It is often dyed red so that it is easier to detect bad seals or a cracked hub – if it was not dyed you could easily mistake the oil residue as engine oil.
The prop pitch changing is accomplished using engine oil working against counterweights which are also located in the propeller hub. The aerodynamic and centrifugal forces are tremendous, so the engine oil going to the propeller pitch change mechanism is routed through the propeller governor, which boosts the oil pressure. The pilot controls the pitch through the cockpit prop control, setting a desired RPM. The prop control is connected to the prop governor, which provides the oil pressure to increase or decrease the prop pitch to maintain the requested RPM.
You can read more about constant speed propellers in the FAA Airplane Flying Handbook (FAA-H-8083-3A), Chapter 11, Transitioning to Complex Aircraft. It is available for free online in PDF format.
I hope that helps.