An interesting statistic would be whether the turbo increases the risk of an engine failure – I suspect on modern equipment, not much, although there are additional failure points.
RobertL18C wrote:
An interesting statistic would be whether the turbo increases the risk of an engine failure – I suspect on modern equipment, not much, although there are additional failure points.
It must slightly increase the risk. But engine failure due to mechanical factors is still a terribly low risk with modern aircraft.
Peter wrote:
Example: on any EuroGA fly-in, we get about 1/3 AOG rate.
I think that this statement does have absolutely no value towards valuation of GA aircraft reliability as this high rate of AOG is in 90% just an excuse of people who decide not to come to the fly-in but are unwilling to disclose the real reason for cancelling the trip. In fact, the turbo aircraft might eventually push down this high AOG rate as I can imagine that in quite many cases the real reason is less than ideal weather that prevents the potential attendees from flying to the meeting. Having more capable turbo equipped airplanes might actually result in higher number of people turning up. I think that the worst enemy in GA flying being used for real travelling is the weather not the equipment reliability.
in 90% just an excuse of people who decide not to come to the fly-in but are unwilling to disclose the real reason for cancelling the trip
I am sure that is true in some cases, but a lot of the time I know the people concerned. Downtime is generally high in GA. It’s a much bigger issue than you read on forums; most people don’t talk about it.
the worst enemy in GA flying being used for real travelling is the weather not the equipment reliability.
That will always be true – unless you have a TP or a jet and fly between ILS runways (which is exactly what most TP and jet owners do; they don’t fly to Wangen-Lachen or Zell am See 
). I used to know a 421C owner who during a particular year did 50 customer visits and had to cancel just two of them (both due to widespread TS) but IIRC all his flights were between big ILS airports. He has since sold the 421 and bought a King Air
Here is one data point, FWIW, overhaul costs fresh from a top US shop:
IO540-C4D5D – $35k (TB20)
TIO540-AB1AD – $62k (TB21)
Both prices assume crank and case will repair.
The TIO price assumes the turbo system and the exhaust will repair. That is a significant assumption. Normally turbo engine rework includes the exhaust which by the time you are doing a top overhaul need some “attention” simply because the engine has been working so much harder for so much longer and doing so in thin air which has a lot less thermal conductivity. The lower OAT at altitude doesn’t help because it is the delta-T which drives the heat loss and when one part is around 600-700C the lower OAT doesn’t do anything (for the exhaust).
Defend the wrong decision?
Absolutely not. When i bought the SR22 that was 13 years after i had flown one for the first one, and while i was searching for the right plane, which took me 4 months, it was clear very soon that i wanted an NA version – for the above reasons.
The airplane can really do everything i need – so why would i buy one with even higher maintenance cost when my typical mission does not require it? Very early i decided that i do not want to to fly in FL250, i find it too risky. And the NAs climb rate to FL140 or 160, is absolutely sufficient.
Pilots are simply different. I know a professional pilot who ordered a SR22 G5 without ANY TKS and oxygen – he prefers the high speed and payload on nice days and only flies IFR when it’s nice. I see no reason to judge these personal decisions.
In numerous icing encounters (some of them leading to “maybe I should stop flying altogether” thoughts after landing) I have never had any problems with ice on the prop.
As the propeller is the source of thrust, and also will experience the lowest pressure (bernoulli), it is where ice forms first. It may not be obvious in a single engine, but moderate icing in a twin engine will lead to ice being slung on the nose. Hence teflon guards to absorb the impact. The ice that hits the nose, is both loud, and quite quickly takes the paint off. This is with propeller anti icing.
Moderate icing in a FIKI twin, with considerable more excess thrust than a single, will reduce performance quite dramatically, especially in flight levels. Climb rates of 600-800 fpm turn to 200 fpm and KIAS drops from 145 to 110 – 120. The twin is also getting induced airflow over the wings from the propellers.
No airline would accept this level of degraded performance.
Is there a non-turbo/turbine single which has achieved FIKI certification?
Alexis wrote:
i do not want to to fly in FL250, i find it too risky
Because it’s mentioned so often – does anyone know any statistic of actual accidents related to failure of oxygen-systems (in non pressurized aircraft)?
I don’t have statistics, but there have been bad accidents even in pressurized aircraft.
The danger i see: When is it that i need to fly in FL250? Definitely not when i can safely fly lower. A malfunctioning O2 system therefore is too dangerous for my taste. Sure, it is possible to have some redundancy with a second bottle, regulator …. but since the TUC in FL250 is around three minutes i find it too risky.
And what do you do if you have a failure? Descend into IMC in an emergency descent while trying to fix it? No thanks.
RobertL18C wrote:
As the propeller is the source of thrust, and also will experience the lowest pressure (bernoulli), it is where ice forms first.
Not in my aircraft. The leading edges of the wing collect lots of ice while the propeller doesn’t. I have enough experience with icing and how it impacts my aircraft to be able to draw that conclusion. I don’t know why it is like that.
