It is fuel temp/pressure not an OAT/DA limitation, I don’t know fuel temp at the pump but it is usually very cold and take time to heat up: so parking your aircraft in hangar, leaving tanks empty and quick fuel and depart will probably do the job on Mogas/UL91 temp issues…
Again load of aircraft that flies on airfields with mogas tend to have other own risks: single ignition, no mixture, no electric fuel pump, the kind to build hours rather than go to places…
There are various past threads on Mogas (a search for mogas digs them out). I recall seeing info suggesting that with an appropriate design of the fuel system, optionally including the constant use of an appropriately located electric pump, you can sidestep these issues.
It is in many cases a requirement of the STC for Avgas burners.
Peter wrote:
The UK LAA puts a 6000ft / +20C limit on mogas use
What an off thing to do. This is a fuel system thing, not a fuel specific thing.
For completeness, one “high temp factor” is Mogas and there are many past threads on it. One recent one, with some LAA PDFs on the subject, is here. The UK LAA puts a 6000ft / +20C limit on mogas use, which is clearly disregarded by most of its users since – especially the +20C fuel tank temp limit – is totally impractical.
greg_mp wrote:
I have been flying in a DR400-180 around the mountains 3 weeks ago with 1 pax. That was the plan, but 32°C at 5000ft, the plane was not climbing too much, and oil temps as just before red line, so I had to reduce power… I gave up at 6500ft and make a slow descent toward the méditerranée.
I changed the plan to do a slow fly around and land. I was very surprised by such high temperature at that altitude. It was 37°C on the ground (sea level). DR400 climbs like hell, but ISA+25 is not the same thing.
Luckily it wasn’t too convective.
I too fly DR400-180 and flew to Konstanz last week with wife and two kids when the weather was hot but not heatwave that we’re experiencing right now. I noticed some performance issue but not that much at FL065.
If the plane could have issues what Greg experienced I have to seriously reconsider my plan given that safe altitude over the mountains is 5700’. Staying around this altitude I would expect to be bumped around a bit or more in the afternoon heat. I know from experience this is not fun.
Temps above standard really impact the operating ceiling.
The TB20 will do 17k with ISA+15, 20k with ISA (21k if slightly light; that’s the highest I have taken it) and would probably do 22-23k with ISA-15.
The problem is that during the part of the year when most of us fly to “nice places” i.e. May to September, the temp tends to be ISA+15. Combine this with crossing the Alps and you can find it a struggle if there is convective wx. The tops can rise as quickly as the plane can climb!
So when there is terrain involved one needs to adopt defensive methods e.g. climb as high as possible (and also flying a part of the desired route i.e. burning off some fuel) before crossing the Alps. So for example when flying back from the Adriatic, LDLO-EGKA in this example, the flight runs all the way to DESIP, burning off fuel and giving time to climb, while providing an opportunity to eyeball the conditions over the mountains, before heading across them.
The TB20 is relatively powerful (250HP) and has a decent altitude capability. When you go down the power range to the popular GA planes you will see this problem much lower down, which can really affect your ability to fly in proximity to some of the terrain found in parts of Europe.
I have been flying in a DR400-180 around the mountains 3 weeks ago with 1 pax. That was the plan, but 32°C at 5000ft, the plane was not climbing too much, and oil temps as just before red line, so I had to reduce power… I gave up at 6500ft and make a slow descent toward the méditerranée.
I changed the plan to do a slow fly around and land. I was very surprised by such high temperature at that altitude. It was 37°C on the ground (sea level). DR400 climbs like hell, but ISA+25 is not the same thing.
Luckily it wasn’t too convective.
And another funny incident I overheard two days ago on Langen Information: a Super Puma crew (so I think federal police) discovered a forest fire, and approaching it noticed it was inside the Hammelburg restricted area. Langen called the military while the helicopter crew, who had some water to drop on board, duly waited outside the R area. Some time later they got told that they could not get a clearance and the military would maybe fight the fire themselves…
Noteworthy is that the Bundeswehr have burnt down large areas of northern Germany in the past months around their exercise areas.
Many useful tips and much appreciated.
:)
