Congratulations Patrick! The B58 is a great airplane!
Pressurised with radar?
Peter, no and yes.
I’m in a Baron 58 (which is unpressurized, normally aspirated engines), not a 58P (which is the pressurized, turboed version).
I do have weather radar, boots, hot props, heated windshield… I will have stormscope, TCAS, and some other gadgets including GTN750 when I get it back from the avionics shop, hopefully next week.
Re-reading this thread, realizing what a small world this is, pretty sure RobertL was my flight instructor for my first hours in a twin, if I’m mapping online profile to the real world human correctly… Had to depart for sunny California before I could complete my EASA AMEL training and opted to just go FAA all the way.
Return to Europe with my twin has been delayed, probably for another school year for the kids, as has the return of my plane with completed avionics upgrades… Do these projects ever get done on time?
While high time airframe this seems a practical value IFR twin.
Irrationally, people are terrified of high time planes. But they’re happy to step on a BA 747 with 100.000hrs on it certified to the exact same Normal Category standard…
Hodja wrote:
LeSving just curious, what would the rate be with triple & quad redundant systems?
Triple would have MTTF 11/6 times (83 %) higher than single and quad 25/12 times (108 %) higher than a single. E.g. if you take an engine with MTTF of 1.000 hours, you would get 1.500 hours with two, 1.833 hours with three and 2.083 hours with four engines to failure of all units. But this is on assumption that no repairs are done (hence MTTF).
What does that mean? Well, if you have two said engines, you should on average experience a failure every 500 hours. But if you don’t repair that failed engine, you only have one engine and that will fail on average after 1.000 hours. So you get total failure on average after 1.500 hours. If you start with three engines, first failure should come on average after 333 hours. After which you have two engines so 500 hours to the next failure and then one engine so 1.000 hours which gives you that nice number of 1.833 hours (1.500 + 333). And so on and so on. There is an assumption of no memory so the engine(s) lucky to remain have no knowledge of what was before.
In a repairable system, which an aeroplane is, it comes down to how long it takes you to repair or replace the failed component, restore the system. In this case, how long you fly OEI. The longer it takes you to land to make repairs, the more likely is another engine to fail. If you take two of my hypothetical engines and it takes you on average two hours to land after you lose that first engine, MTTF is mean time to first failure (500 hours) times mean time to second failure (1.000 hours) divided by the time it takes you to land (2 hours) which gives you 250.000 hours. Quite an improvement over 1.500 hours. And you can improve it further by landing sooner.
Obviously, reality is more complicated than that. This is more for amusement.
Airborne Again wrote:
Since flight times are very short compared to the MTBFs, I never considered that the flight time could have any practical impact on the decision between a MEP and SET, but apparently it does.
It’s not actually the flight time, but the time it takes you to divert/ land. The difference between single and twin being that MTTF of a single isn’t dependent on this at all, it will give you the same probability of failure wherever you are, while twin will give you higher probability of complete failure the further away you are from a suitable “surface” (assuming you can actually fly on one engine) because you can’t replace/ repair an engine while airborne and all that time you’re a single.
So yes, in the EU with plenty of airports, a MEP might beat a SET in MTTF. If a turbine is a hundred times better than piston engine in terms of MTTF and that piston engine is in the order of thousands of hours, hundred just won’t cut it. You would need a long ocean crossing with no possibility to divert to bring it down on par. However, the MTBF of the twin would be poor in comparison (you might not crash land, but you would be getting failures way more often on average which would have to be fixed).
Again, just for amusement. Engine probably won’t be the thing that kills you.
I assume the loss of one piston engine increases risk to the other due to the higher power setting needed to fly OEI.
Fuel mismanagement/contamination/icing is possibly the main cause of double engine failures on twins?
