Fluctuating Oil Pressure

Original Plan to KFFC

We had a very busy Friday night so missed our start time on Saturday. We were in the plane heading for the run-up by 10:30. It was a beautiful day, clear skies and light winds. We took off on Rwy36 and departed to the north, picked up Flight Following through the busy Tampa airspace and climbed to 4500ft. I completed the climb/cruise checklist and settled in for the 2+ hour flight to our fuel stop at KMGR. Tampa cancelled Flight Following just north of the Class B. We were just above the haze layer and found headwinds at about 25-30kts but smooth air. After about 45 minutes I saw the flicker. Oil pressure dropped into the yellow but immediately recovered to nominal in the green. I thought about all of the work that had just been completed. For the next five minutes it fluctuated about 10psi but stayed green. I relaxed a bit, but made my contingency plan. Where are the airports along this route? Then another dip into the yellow. Any vibration? Any other indications? Any changes in engine temperatures? Any visible oil film? All answers were "no".

Then she dropped into the red. "We are aborting the flight", I told Kathy. I immediately clicked off the autopilot and turned right. Crystal River was slightly south and doable. Oil Pressure went back to green. Went through my checks again. Was there ANY other indication? No. "I think we'll go home". With the tail winds it should be about 30 minutes. Back in the red, reading 0, then 2 psi, for just a second then green. Still no other indications. Then back in the red for 5 seconds.

The closest airport with the longest runway was Brooksville (KBKV). Kathy asked if she could help, she could see I was busy. I told her my intentions to land at Brooksville about 15 miles ahead of us. I love my 696. I dialed up tower and told them I had fluctuating oil pressure, and gave my position. The Tower guys were GREAT!. He asked me to call a 3 mile base for Rwy9 and he worked on clearing traffic out of my way. A C130 was in the pattern doing parachute drops, and a few other planes were vectored out of our way. I came in high (intentionally) and started to slip her in once on final. Nice to have a 7000ft runway. We turned off at the first taxiway and made our way over to the FBO.

GA Knights.

It's a Saturday morning and you need a professional mechanic. Say you're at home and need a plumber or an electrician or whatever. You know it is not going to be a good experience. But this is General Aviation. We walked into the FBO and were treated like friends. No mechanic on duty but there is a group of guys working on their airplane in one of the hangars. He is an A&P and may be able to help. Within 10 minutes Nathan, Chris and James come driving up in a golf cart. James is A/P I/A but hasn't any experience with ROTAX Engines. But he CAN trouble shoot some common problems.  After some time to scrutinize the systems he takes a look at the oil pressure sending unit. One of the pins in the connector is loose. Maybe the smoking gun? He puts it all back together and we do a run up. All good. He cautions that there might be something more serious but without doing more in depth analysis he couldn't be sure. I thanked him for the help and asked what I owed. "Nothing, just glad to help."

I also called Patrick at US SPORT for his advice. He was out flying, but when he returned immediately called back and left a message. From the description I provided he suspected the sensor.

I put the cowling back on and told Kathy to wait in the FBO while I went for a test run. The test flight was all good. I picked Kathy up at the FBO and flew the 10 minutes back to Tampa Executive. I'll take her back down to Sebring for a "more in depth analysis".

We all gripe about the costs of flying, the over regulation, and all of the annoyances we face each time we go out to fly. We don't talk enough about the wonderful community that we have. Complete strangers treating us like family. What a privilege it is to be a part of GA.

at Lockwood

Another Logbook entry

Its been 5 years. We flew Sally home to Butter Valley from Florida in December 2010 and really started flying operations in the winter months beginning 2011. The Rotax Line Maintenance manual says that every 5 years a full rubber replacement must be done on the 912ULS engine. I called Lockwood Aviation Repair to get an estimate (about $3K) and made the appointment to get it done. As I checked my logs it also made sense to get a Condition Inspection done. Since I was already getting some work done, Joe gave me a price break ($0.5K).

During those first few cold months of ownership in 2011 I made a mistake. At that time my preflight did NOT include removing the upper cowling, instead just opening the oil access door and peeking inside. It has since changed, but at the time I thought it was sufficient. (Especially on a really cold February morning.) Runup and all ground ops were normal. But during the take off roll I got a CHT High warning. Too late to abort I made one lap and landed. The old coolant bottle had a design defect that allowed the tube to come loose from the cap. Mine had done that, robbing the needed coolant from the engine. Overheat.

So when I mentioned to Joe that I had a minor oil leak, Joe thought it was probably loose head fasteners needing to be re-torqued. She had also, just recently started to have a coolant leak. Then I got "the" phone call. That hot flight 5 years ago had damaged the heads. The heat had taken the temper out of the aluminum. 3 of the 4 heads would have to be replaced, and the 4th was right on the edge of the hardness test. Expletives, etc.

So Sally got 4 of the new and improved style heads installed. ($6K). Except for a few minor problems (left break pads, ELT batteries) had a good Condition Inspection. Joe said she should be ready on Monday. Then I got "the" phone call. Joe wanted to know if I had any start problems. Until recently she started after a few blades. Well, not anymore. Test showed that the ignition modules were in the process of failing. Expletives, etc.

So Sally got the new and improved style soft start ignition modules. ($2K).

Yes, she DOES run better, has more power, runs smoother, starts easier. I'm relieved to have her back and so grateful we didn't have a problem while flying. I'm also VERY glad to have found our new A&P.

I think she needs a good test flight.