Alright, let’s just call May a complete write-off!! What a miserable month for flying. The couple of nice days found us at our cabin. The result was a one-month gap in flying for me.

Fortunately, this weekend was more seasonable, and it allowed me to aviate. On Friday, I decided to take the day off to handle some chores but decided that the weather was just too nice to stay in town. I had a neighbor that had been asking me to take him flying so that he could get some aerial photos of his place in Crossfield so away we went.

The weekend was topped off by a flight to Lacombe with my wife Renée, to take in the annual fly-in breakfast. Renée doesn’t often come flying with me since I usually end up going for most of the day, longer than she can handle aviation in one sitting . Fortunately, the day was wonderful, and we had a great time visiting with friends in Lacombe.

Once we returned to Carstairs, I dug into the annual inspection on the Christavia. I was quite surprised to see that after six years of flying, the cylinders are all still showing 78/80 compressions. In general, the plane is still in great shape.

One new addition that I’ll be adding this year is a spinner. I was able to find one from Great Plains Engines that seems to fit with some minor modification. The spinner is a blank that allows me to cut it to fit the Franklin’s unique hub pattern. The big advantage of installing a spinner is that I can now dynamically balance the engine and propeller. I’ve done a number of dynamic balances over the past year and have been amazed at just how smooth an engine can be made to run. The problem I’ve had has been that I had nowhere to mount the weights needed to balance the engine properly.

Most props are statically balanced by the factory or overhaul shop that services them. However, the prop is not a stationary object. Think of a teeter-totter with a kid on either end. One kid weighs 50 lbs and the other 75 lbs. It is quite easy to statically balance the teeter-totter by moving the heavier kid closer to the pivot point. The same thing can occur with a propeller. If you start spinning a statically balanced propeller, it could cause a vibration in the airplane. Additionally, the rotating parts of the engine itself may not perfectly balanced causing yet another source of vibration.

This vibration can result in premature wear on the engine and fatigue damage to airframe structures; not to mention the toll it can take on crew and passengers over long flights. By using a vibration analyzer, weights can be added at specified points on the rotating parts to reduce or eliminate the vibration.

Vibration analysis is also a good tool to trend the health of other rotating components on the aircraft. The vibration that is corrected is usually done at cruise RPM, say 2300 or so. The spectrum analysis done by the analyzer looks at vibration peaks which occur at other RPMs. By comparing these peaks over time, the reliability of certain components can be predicted. For example, let’s say that there is a vibration peak at 66,000 RPM on a Piper Malibu. It stays relatively constant at 0.04 IPS (IPS is a unit of vibration) over several years but suddenly starts to increase. On a turbo-charged engine, 66,000 RPM is the speed of the turbo-charger itself. It may be time to replace it before it fails.

Granted, this level of analysis on a plane powered by a Continental A-65 is unlikely to be worth the time or cost involved for trending. However, the initial dynamic balancing is very useful.

If you do plan on having a dynamic balance done, it should be done after the engine/airframe and prop have had a chance to “break-in”. In other words, wait 50-100 hours after an engine overhaul, top overhaul, propeller replacement (especially wooden or variable pitch types) or replacement of engine mount bushings.

And now for something completely different … In April, I flew Pat Cunningham to Springbank to pick up his Cessna 120. Normally, the Garmin 296 comes up with five or more satellites in about 15-30 seconds. This time, I got NOTHING! It looked like I’d have to go back to the old dead reckoning style of navigation. I started to think about what might have changed since the previous flight that could have caused the GPS failure. I was just about to take-off when I figured it out… The new iPhone 3GS! Sure enough, I switched the iPhone into “Airplane Mode” and 6 satellites immediately popped up. I guess those warnings given by the airlines all these years were valid!