We really had picked some great flying weather for our trip to Scotland. There are not so many days you can get a VFR clearance through the Glasgow zone at FL85. We filled G-EJBI with fuel and then departed for a very scenic flight on our way to Glenforsa. Fuel has not always been available at Oban but it was this summer and the price pretty reasonable.
The Bölkow 207 really excels when it comes to a bit of longer distance touring. Up above five or six thousand feet with the mixture leaned the endurance is well in excess of five hours at a leisurely 110 knot cruise. We were able to take a straight line track from Tibenham to Oban which is pretty unusual for a VFR aircraft in UK airspace, helped by there being not so much Class A airspace in Scotland.
Mid July we flew G-EJBI to Old Warden for their evening airshow. As the flying display finishes around sunset we took a tent and stayed a couple of nights under canvas. An evening airshow and camping in such beautiful grounds is a really wonderful experience. On the Sunday we flew G-EJBI to Sandown on the Isle of Wight for a pleasant day out. Sandown is a very popular spot for visiting light aircraft but they cope well, cook a good pizza and the seaside is not so far away.
We flew four flights during June, all of which were conducted in the local area. A bad habit of mine is to rely on the fuel gauges (plus a certain amount of knowledge of the flight time since last refuelling) to determine the amount of fuel on board the aircraft. When we did our FREDA checks on a local navex and found both fuel guages pretty close to indicating reserve I was a little suprised and a little uncertain of the remaining endurance, Fortunately we were above Rougham airfield and able to pop in for a top up.
It has been five months since G-EJBI last flew and time to hurry up and finish the annual inspection. I am tending to do the work myself with Andrew which is then checked by a local CAA engineer. A local maintenance organisation then reviews the work and issues the ARC certificate. This was all completed mid May and G-EJBI was back flying. My initial impression of the fixed pitch propeller is very favourable with little change to the aircraft performance.
Back in January I realised that a new spinner and attachment plate would be required for the fixed pitch propeller. All the drawings for these parts are available on Claus’s excellent website www,boelkow207.de A firm in Norfolk, who initially seemed keen to fabricate the spinner, eventually admitted defeat when their toolmaker was unable to supply the former to spin the alluminium around. A local engineering firm were going to make the attachment plate and reuse the original spinner but with covid delays I eventually got cold feet, worried about possible ballance issues. I have now ordered an RV alluminium spinner, not technically the correct solution but should loosely qualify as an owner fabricated part and suffice while I sort a more ‘correct’ solution.
Having modified the engine it was time to fit the ‘new’ propeller. I say new but G-EJBI’s new prop is around 20 years old. There is not a lot of U.K. prop stock and what is available is quite pricey. There are also waiting times and delivery costs if importing from the States. I was offered a new but old stock propeller at a reasonable price so that seemed the way forward. Included in the price was an overhaul and fresh paint, it should be good for 2000 hours. The Sensenich propeller fits straight on the hub, which as there is no CSU, places the blades a little further back. This causes a slight problem as the blades are now very close to the lower cowling and the spinner attachment ring is not usable.
An original option with the Bölkow 207 was to have a Sensenich fixed pitch propeller fitted. Not as cool as a constant speed prop and with a performance defecit, I figured it was only a bit less cool and the performance was only marginally poorer. I set about removing the propeller governor with it’s adapter and installing a blanking plate. The oil line is removed, the rear crankshaft plug pierced and a new front plug installed. The engine is now to Lycoming O-360 A2A specification which is a requirement for the fixed pitch prop.
The O-360 engine with a 72″ Hartzell prop is a fairly popular combination but try as I might, I could not find a suitable second hand item. MT Propeller in Germany manufacture a three blade composite prop with the required approval for the 207. It is reassuringly expensive and there would be a three month wait for delivery. I spoke with an owner who had recently fitted the MT prop to his 207, he was very satisfied with the results, particularly the smooth running. I was not so sure the benefits justified the £13,000 price, there must be an alternative and hopefully cheaper solution.
Our Hartzell propeller was sent to the Prop Shop and unfortunately was found to have corrosion on the hub. This was not repairable as no machining is permitted on this component. A replacement hub would have to be specially made by Hartzell and would cost an awful lot of money. A new 2 blade Hartzell propeller which would fit and work perfectly was also not an option as the new model had an alluninium hub, a different serial number and hence no approval for the Bölkow 207.