Cowlings back on again, for the first time in months:
Since the end of July, we had a bit of tinkering to attend to:
Sump oil leak, cylinder head cover oil leak, carburettor sent off for refurbishment, dead number 1 cylinder (new piston rings and cleaned up valves), dead battery and dodgy starter motor.
Finally everything was back together and ground runs completed. No excuse to put it off any longer. Time to fly.
A general wazz around just to the north of the airfield, keeping close in case we needed to get back in a hurry. Note the trace showing a simulated circuit pattern just over the A984 symbol…this was to check the engine response in a balked landing when full power is needed in a hurry.
All was satisfactory so it was back to the airfield for circuit practise. This was to exercise the engine through the whole range of power settings and had the added benefit of landing practise for me.
With hardly any wind the duty runway was the east west one. This goes right past the clubhouse windows. And everybody is watching (and grading) the landings. No pressure, then…especially as fellow helicopter pilot Chris (who also flies an RV3 and is building an RV14, see http://www.vansrv14.uk/) had just landed and was undoubtedly watching with the rest of the vultures.
Several landings later and the aircraft was still in one piece and capable of being taxied off the runway, so the landings can’t have been TOO bad. The RV grin is back!
As usual the landing debrief from the gallery was brutal. They take no prisoners. Not to worry, the aircraft flies again! Plus it was time for me to join the grading team and watch some landings for a bit…no pressure!
“If all goes well, it’s back into the air. Can’t wait…“
All didn’t go well. We ran the engine to set up the idle mixture on the carburettor and there was a lot of vibration. Cylinder head temperature (CHT) on number one cylinder was way down, almost as if it wasn’t firing.
Well, no “almost as if” about it. It wasn’t firing. We swapped sparkplugs around and checked ignition leads to try and isolate the fault, but it stubbornly remained.
Inspector Sandy started to suspect a stuck valve, which would be allowing the fuel/air mixture to leak away, so next step was a compression check to check how well each cylinder held its pressure…
With an input pressure of 80 psi, cylinders 2,3 and 4 were losing between 5 and 7 psi – those are pretty good compressions.
Cylinder 1 was losing 64 psi – that’s a pretty BAD compression. Obviously.
Cover off and inspection of the valve rockers revealed movement, so no stuck valve. We began to suspect worn piston rings. For this, the cylinder would have to come off. Time to get the tools out again…
A sorry looking engine. To get to this stage involved removing the inlet tube, exhaust gas temperature (EGT) probe, cylinder heat temperature (CHT) probe, exhaust, fuel prime pipe, oil return line, front baffle, lower baffle, spark plugs and ignition leads, cylinder and piston head. We found the problem.
Worn piston rings confirmed. The gaps were way oversize and had also migrated round so that all three were lined up, providing an easy wide pathway for the fuel/air mixture to just hiss away on the compression stroke, leaving nothing to ignite when the spark plugs fired…(two plugs per cylinder, it’s an aviation thing…)
New piston rings aren’t cheap…ask me how I know. While they were on order Sandy took the time to clean up the piston, cylinder and valves as they were a bit manky. All normal for an 1800 hour engine, but why not?
The piston crown before:
The same piston and one of the valves after cleanup:
We had a little trouble with the valve collets, they are the little semi-circular pieces by the spring:
So I took them over to Bob in the next hangar. We had struggled over a whole lunchtime to get them out, but Bob had them out in 10 seconds, plus another 10 seconds to put them back in a few days later…It’s amazing what the correct tool can do!
Sandy fabricated a valve ring compressor tool for getting the cylinder back on:
…and after about 10 minutes of huffing and puffing and maybe the odd swear word, we got the cylinder over the piston rings and onto the engine. Cylinder bolts tightened up to the correct torque, all I need to do now is reverse the process and get all those bits back on, then several ground runs (…including the one to set the idle mixture which we were half way through when this problem surfaced…) and a specific flight profile to get the piston rings bedded in. We’ll be flying again by Tuesday.
I’m not committing to WHICH Tuesday though. I’ve learnt my lesson.
I was going to call this “Oil’s well that ends well”, having finished rectification of the oil leak…but it didn’t end well.
There was a bit of faltering in the engine during the ground run to check for leaks, almost as if the mixture was running too rich – too much fuel starving the fuel air mixture of air.
After shut down we found fuel dripping from the air filter box under the carburettor. Time to get the tools out again.
Disconnecting the air box revealed the carb intake:
…and I lay under the aircraft with the fuel controls at different settings to see what would happen. There was a persistent drip of fuel from the “float bowl atmospheric vent”, which as the name suggests, should probably be filled with air rather than fuel. This fuel would be getting into the carb throat and richening the mixture. We decided to remove the carb completely and investigate further.
The fuel lines and control rods were disconnected and the carb removed. Note the use of tie wraps to annotate which control rod is which, red for mixture, white for throttle. It should be impossible to connect them up wrongly, but where there’s an idiot, there’s a way. The nuts are rethreaded onto the bolt threads for the same reason, to stop them getting lost.
Tie wraps are wonderful things. Taking the carb off involved several different sizes of spanner, and it would be nice to have them easily to hand when it is time to reassemble, so I tied them together rather than throwing them back in the tool box:
…and also took some notes as to which spanners are used where:
Once the carb was off I decided to send it off for an overhaul so that the experts could rectify the problem. It had done 1800 hours and was probably due for one anyway, and getting it done professionally gives added peace of mind. Here it is just after removal:
And here it is ready to dispatch. I chose Nicholson McLaren to do the work because they have a good reputation and they were the most “economic” quote! They featured in a video by Jon Hunt, see:
Just a week later and it’s back, freshly overhauled and beautifully packaged. It’s lovely and shiny, almost looks new…
It arrived back just in time for my return to work. Typical. Luckily all was not lost…there was a bit of preparation required, so I did that at work, in between flying…and who says men can’t multitask?
Next week, refitting and ground run to set up the idle mixture. Sandy the inspector is helping with that one. Sooner him than me crawling around under a running engine fiddling with an adjustment nut right next to hot exhausts.
If all goes well, it’s back into the air. Can’t wait…
Attributed to astronaut Alan B. Shepard, the first American in space. It is usually quoted as “Dear Lord, please don’t let me f**k up” – which is exactly how I felt as I started towards the engine with tools and intent. Time to investigate the oil leak.
Pretty sure it was coming from the oil sump gasket, I realised that to change the gasket would involve taking at least the four inlet tubes off, and if the sump didn’t drop far enough, the exhausts too.
The tubes came off quite easily:
But is was still a little crowded under there:
And the exhausts would have to come off. Great.
Once the exhausts were off it made it a lot easier to get at the sump bolts:
But eagle-eyed readers with a bit of Lycoming O-320 knowledge will notice that the starter motor is removed too. That sucker was preventing me getting at just one of the sump bolts. One bolt. And that starter motor is heavy. So to get at one bolt I had to undo another five bolts, four spacers and two plates. Even minor tinkering grows arms and legs.
Once I could get at the bolts it was relatively straightforward to drop the sump and remove the old gasket. You can see the new one ready to go in the photo above.
Before putting it all back together I had to order new exhaust gaskets, inlet gaskets, new hose for the warm air ducts, new exhaust bolts and washers. Once they arrived it was relatively straightforward to get it all back together. With no parts left over. Always a bonus.
Time for a ground run to check for leaks. Filled with oil and a sploosh of “Camguard” – it guards the cams, what else can I say? I started up, checked oil pressure and temperature rising, let it run for about a minute and shut down. I jumped out and had a good look around the engine. No leaks.
Then it hit me – the engine started! I didn’t f**k up putting the starter motor back on. Ole Shepard produced an effective prayer, I’ll be using it regularly.
Another run, this time for about five minutes and up to 1700rpm for an ignition check. All looked good so we shut down and put the aircraft back in the hangar.
I was tidying up the tools when I noticed this under the left side of the engine:
And it was getting bigger! Bugger. I followed the drops back up to the source and found leaks at the base of both left side cylinder head covers. Removing both revealed splits in the silcone rubber gaskets:
Definitely a route for oil to leak out. They’ll need to be replaced. Here we go off to the Light Aero Spares website again…they must love me.
New ones are on order (£7.77 each)…but I’m back at work so tinkering will have to wait for a few days.
At least the oil sump has a new gasket, whether it needed one or not…
It’s pretty cool staying on an air park. Neighbour Robert invited me for an evening flight in his Savage, a Rotax 912 powered two seat tandem Piper Cub lookalike from Zlin Aviation in the Czech Republic. We made our way out along taxiway Bravo past another Czech aircraft, a Danish registered TL Sirius (brother to our previously owned Sting)…
…and backtracked to the other end of the runway:
Before taking off into the evening sun:
Great views of the air park village as we climbed out. Zoom in enough and you can see Robert’s Jeep:
Climbing out on downwind, Lake Siljan in the background. Plus lots of trees:
Lots of lakes and lots of trees. One thing was puzzling me though, the Savage is German registered and the cockpit is covered in placards like OELKLAPPE and RADBETRIEB and ANFLUGSGESHWINDIGKEIT and SKISTELLUNG and KRAFTSTOFFSVORRAT…so why does it say NO PUSH on the wing struts?
One of life’s mysteries to ponder as we floated along enjoying the view. Mostly trees and lakes with a bit of lakes and trees mixed in, together with the occasional settlement of little Swedish houses and barns…
Mostly trees and lakes makes navigation quite tricky, the map is predominately green. Main roads, railways and logging roads make good line features for crosschecking progress and are here laid out for demonstration purposes:
Really distinctive line features are the power lines running along their own fire break style gap in the trees. These stretch off into the distance and the eye can follow them almost all the way to the horizon
It was about a 30 minute flight to Malung Skinnlanda airfield which lies just beside the river a little bit south of town:
There was a gyrocopter on the frequency operating to the west, but the airfield was deserted as we landed, shut down and got out for a stretch:
The Savage is a lovely little aircraft and draws a crowd wherever it lands:
One elderly airport guy wandered over. He didn’t speak English or German but we communicated in fractured Swedish. I managed to tell him we didn’t need any fuel and he gave a long rambling description of something about Dala Järna airfield and potatoes. I think. I couldn’t confirm with Robert as he had wandered off for a pee by this point.
We tried the clubhouse door but it was locked. Next time I’ll leave a 100 SEK donation. 10 Swedish kronor is about £1, the smaller rural airfields don’t usually have a fixed landing fee, or any fee at all, but most of them are run by clubs and a donation is welcome.
We climbed back in and set off again. The front seater has a panel mount moving map GPS to help with the navigation over the sea of green, it’s not just line features. There was also a map in a side pocket, an iPad with Foreflight and my phone was running Skydemon so we were unlikely to get very lost…
Turning for home over the Västerdalälven river:
Through the overhead of Dala Järna airfield (of the potatoes story fame). It’s only a ten minute walk to the supermarket from the airfield…I want to fly there next time Brenda sends me out for milk, or potatoes. Maybe the mystery of the story will be resolved
Past Brasjön where Brenda and I had good fun in the morning with our inflatable kayak. Brasjön translates as “The good lake”…
And then onto final where Robert flew a nicely flown sideslipping approach to the grass runway 14.
As we were taxying in, Alexander gesticulated with the universally accepted drinking sign so we stopped and abandoned the aircraft on the taxiway:
A lovely evening flight with a beer at the end. Like I said earlier, staying on an air park is pretty cool…
In Sweden for the 30th annual fly-in at Siljansnäs Flygklubb, also known as the highly unpronouncable “Kräftstjärtsvängen” – something to do with crayfish. In past years this event has attracted lots of visitors; one year had 78 aircraft logged in as early arrivals on the day before, and many more on the actual day.
This year the weather forecast wasn’t looking too good for the day itself, but Friday saw a handful of early arrivals from Sweden and Norway in lovely weather:
The highlight of Friday evening is the car show “Åkdon och Termos” which translates as rides and thermos, kind of like a flash mob for classic car enthusiasts, with coffee. Some seriously cool old (and not so old) cars on display…
Walking home it was easy to convince ourselves that the forecast would be wrong…
…but it wasn’t. Rain and low cloud. One of the early arrivals from the previous day bugged out early to get home before the weather, and was replaced by a Cessna 206 amphibian – the sole arrival of the day. Airpark resident Niklas did his Saab Safir display to keep the small number of attendants interested. The flygklubb had put their 3 gliders and the tug out, giving a total of seven aircraft visible:
As the rain increased, the stalwart announcer in the tent out on the flightline kept up with the commentary:
The rain got even heavier and eventually the last few hardy souls called it a day. At least in the burger tent we were doing a roaring trade, and inside the clubhouse Brenda was also kept busy selling coffee and buns and working on her Swedish at the same time. Every year airpark residents volunteer to help, this year we were on burgers and coffee. Our neighbour Robert kind of took over the burger duties so I was left on tidying up. I forgave him later as he gave me a lift home in his Jeep. A real green Willys Jeep. The best bit of the day. Robert’s philosophy is “He who dies with the most toys, wins!”
By mid afternoon it was all over bar the jeep ride:
The recently installed awning on the clubhouse deck was threatening collapse and had to be drained regularly:
But later on the hangar party was great as always…food and drink (including the aforementioned crayfish) with visitors, club members and airpark residents. Good time had by all…I woke the next morning to find that I had won a toolbox. Don’t know why, but…toolbox!
If anybody is looking for a Bellanca, the one in the background is for sale:
Typical weather messing things up with the plans of puny humans. It was lovely and flyable either side of the weekend (post to come soon) but that’s the way of things. There’s always next year…
Post flight checks revealed oil dripping from the lower cowling. Not a giant deluge but not normal for this engine, which is usually nice and dry. Other engines leak to differing degrees…Danny in North Carolina flies a Chipmunk with an old Gipsy Major engine which leaks a lot – he says if it’s not leaking that’s the time to start worrying. In our case, any leak is a concern, so a little bit of investigation was called for…
Cowlings off and having a look. We found oil inside the left side of the lower cowl but not the right. A closer look on the left side of the engine revealed what looked like a leak from the oil sump gasket. We have a spare one in the parts cupboard so that’s good. Not so good it’s quite fiddly to get to. I was having a rant but Brenda said “Taking bits off is a great way to get to know your engine” – and she’s right.
The sump is on the bottom of the engine and will need to be lowered. It’s obviously easier to do that when it’s light and not full of oil, and as we’d just landed the oil was warm and free flowing so I decided to drain the tank there and then.
Draining the oil on both the Eindecker and the Sting could be messy processes, but this engine is fitted with a quick release drain plug. The standard is just a drain plug which unscrews…at some point in the process the oil starts to flow all over and around the spanner in all sorts of strange directions, and once removed the plug usually needs to be fished out of a pan of hot oil. It can be a very filthy task.
The quick drain makes it clean, simple and spannerless. Just position the receiving funnel underneath, push up on the drain to open, and turn a quarter turn to lock it open. Stand back and admire the oil flowing with no mess. All for $100.
Whoever designed this quick release drain is a genius. So simple but so effective. When we build our aircraft we’ll definitely incorporate one.
Another new toy for the aircraft, although this one isn’t a toy and could save our lives. You can just spot it in the bottom left corner of the windscreen:
A closer look:
It’s a SkyEcho electronic conspicuity unit, with a built in GPS which feeds a transmitter to send out our aircraft’s location, and a receiver to take in information from other sources. At the moment the transmitter is inhibited, as the RV has a Mode-S transponder which already sends out our position to ATC, but the UK is working towards allowing electronic conspicuity devices and transponders to both transmit from the same aircraft. This will enable other people to see us, rather than us just seeing them.
The SkyEcho feeds the Skydemon programme on the iPad…sitting on the ground at Perth we were able to see airliners over Oban just about to head out over the Atlantic:
And the smaller traffic display in the corner of the map also showed nearby targets. This one is a Cessna approaching the airfield 1500ft above us:
Seeing how it works in the air was a thinly veiled excuse to go flying. Airborne from Perth and heading west, past the “Rewind” festival at Scone Palace:
Heading south into Fife and back we could see all the airliners going into Edinburgh on the screen, but nothing came close for a screenshot until we were passing RAF Leuchars. Delta Airlines (probably a Boeing 777) passed on our left with about a mile clearance. Luckily it was 29,700 feet above us at the time:
It was quiet but eventually we got a target at our level. The display shows a Robin DR500 G-GMIB on a converging course and 1000ft below us. It’s depicted in green but if it’s an imminent threat it probably turns red. We didn’t try to check that theory!
So we now have a pretty useful traffic awareness tool for when we’re flying around. I’ve also paid for the “FLARM rights” which means it will pick up and decode the glider beacons as well. It doesn’t show ALL the traffic though…most military stuff won’t show up and also some microlights and light aircraft with no transponder or an older type. In that respect it’s just like the Flightradar24 website – not all aircraft appear on the screen.
The thing to remember is that this is an AID, not a cure all. There is no substitute for actually looking out with the good old “Mark 1 Eyeball” – but it is another layer of safety. Plus it’s pretty cool.
Talking of Flightradar24, the trace of the flight showed a quite healthy speed, one that the RV6 could only achieve in real life if you took the wings off and dropped it from a helicopter at 10,000ft. (Do not try this at home, do not occupy the aircraft during this exercise.)
The traces are not always accurate. Remember that the next time there is an incident and the news people are analysing Flightradar:
379 knots groundspeed would make for a good touring aircraft though…if only.
Time to fix the Eindecker electricals and remove the “dead weight” radio. But first a blast around in the RV for half an hour…I had done my required one hour with an instructor the day before and needed to get rid of the stink of Cessna.
Wing overs, steep turns, a practise forced landing and a general wazz about, followed by a crosswind landing in blustery conditions. The aircraft explored the width of the runway while I tried to get it slowed down. Not to worry, we just practise on narrower and narrower runways until I get it right!
The upper winds were quite brisk, leading to an impressive ground speed readout on the GPS at one point:
With the RV back in the hangar, it was time for tools out and investigate behind the Eindecker panel. This is a little convoluted as it requires the removal of the cockpit rim edge leather to get to the screws underneath. This takes most of the time as the lacing has to be undone, then the leather peeled back, then the pipe insulation foam removed and finally the edging strip. After that it’s about 10 screws to undo and the panel slides out:
The cause of the alternator charging problem was quickly apparent: there was a loose connection on the rear end of the ignition switch. Reconnected again and crimped slightly to make sure it doesn’t fall off again, all it needs is a ground run to confirm it is working.
With the panel off it was an easy matter to undo the four mounting screws and slide the radio out, manoeuvring it to disconnect the aerial and connector at the back:
Then to the locker to languish on the shelf…it actually doesn’t weigh very much (416g) so there’s not going to be a massive boost in performance after all. One burger and chips from the soon-to-reopen airfield café will cancel that out…
The one improvement is that I can now connect the aircraft aerial to the handheld radio using the cable that is now free:
The aircraft aerial with its tuned length and ground plane plate (all hidden in the rear fuselage) should be much more efficient that the “rubber duck” style aerial on the handheld:
And just in case you’re wondering, the term “handheld” does not apply when we are floating around at 500ft over Perthshire on patrol daydreaming of Snoopy and the Red Baron; when flying the radio is clipped into a mount on the left side of the cockpit with the press to talk button within easy reach of the throttle hand.
The handheld also comes along in the RV as a backup emergency radio, but its main function is primary radio in the Eindecker.