Engines

Which engine to get is a hard nut to crack. I have updated my list and also included TBO. The reason is that the geography in Norway is very different from the European or American mainland. Good emergency landing spaces are far apart, 99% of the country is either woods, mountains or water, and none of those are good places to land in an emergency. I have to be somewhat lucky to survive, very lucky not to be injured and extremely lucky not to wreck the aircraft. Having flown only in Norway, mostly with certified Lycoming/Continentals or the ever-running Rotax, I haven't given it that much thought until I the engine stopped in a Piper Pawnee last year. I was extremely lucky to be able to glide back to the airfield and make a good power off landing with no damage whatsoever, but will I ever be that lucky again? From a practical point of view surviveability is handled in one of three ways for a single engine aircraft.

1. A very reliable engine.
2. Low impact velocity and or low kinetic energy (low stall speed and low weight).
3. Emergency ballistic system or parachute.

It is obvious from the above list that the single most important factor to protect pilot and airplane is a reliable engine combined with good airmanship (always look for emergency landing spots etc). 2 will most certainly help regarding both surviveability and damage to the aircraft if the engine stops. The Onex do not have a particularly low stall speed, but the weight is low. Number 3 I am not sure is such a good idea at all in relation to the risk of engine stopping. I see 3 as a solution to other cases such as the risk of colliding in gliders or perhaps mechanical failure of the aircraft structure when doing aerobatics.

The only meaningful obtainable number regarding the reliability of an aircraft engine is the TBO. TBO is not the same as MTTF, but it is correlated. A set TBO means the MTTF is well within acceptable limits, if the engine is maintained properly and is operated within the TBO. My general experience also suggests that Lycoming, Continental and Rotax are extremely reliable engines, and these three all have a TBO of 2000+ hours.

With this in mind, the choice of engine becomes more interesting. TBO will be a number to take into consideration. Originally my position was to find an alternative to the Aerovee, one that was not too costly and one that I didn't have to put together myself. Today my position is in fact to find good and relevant reasons (excuses?) for not installing a Rotax 912. This means my engine alternatives have changed and have narrowed down to Rotax, Sauer and ULPower with Jabiru 2200/3300 as possible options.

Name	Type	HP(max)	RPM(max)	cc	kg	Price €	TBO [H]
Rotax	912 UL	80	2200	1300	72	€ 12 142	2 000
Rotax	912 ULS	100	2200	1400	75	€ 13 499	2 000
Rotax	912iS	100	2200	1400	75	€ 18 329	2 000
Sauer	1800 UL	68	3200	1835	64	€ 7 845	1 600
Sauer	2200 UL	85	3000	2234	66	€ 9 567	1 600
Sauer	2400 UL	100	3500	2332	75	€ 10 574	1 600
Sauer	S 2100 ULT	110	3000	2161	76	€ 13 586	1 600
Limbach	L2400 EFI	100	3000	2424	76	€ 23 900	1 600
D-Motor	LF26	92	3000	2690	57	€ 12 600	1 500
ULPower	260i	97	3300	2592	72	€ 14 700	1 500
ULPower	260iS	107	3300	2592	72	€ 15 800	1 500
D-Motor	LF39	130	3000	3993	79	€ 17 800	1 500
ULPower	350i	118	3300	3503	78	€ 18 800	1 500
Limbach	L2400 EB	84	3200	2424	82	€ 19 500	1 400
Verner	Scarlet 7H	110	3500	4127	82	€ 11 990	600
Hummel	2400	85	3600	2400	76	€ 4 850	0
AeroVee	2.1	80	3400	2180	73	€ 5 083	0
Great Plains	2300	80	3600	2276	75	€ 5 199	0
Revmaster	2300	85	3200	2331	77	€ 5 729	0
AeroVee	2.2T	100	3400	2180	80	€ 7 266	0
Viking	Honda	110	2300	1500	81	€ 9 439	0
Jabiru	2200	85	3300	2200	64	€ 11 263	0
Jabiru	3300	120	3300	3300	84	€ 14 460	0

Engines with no TBO (zero TBO) runs in a state of "on condition". This is the same state as a Lycoming/Rotax that has exceeded its TBO runs in. What does this really mean? Well, this is basic maintenance and reliability theories in action in real life. An engine that runs within its TBO has an MTTF or MTBF that is constant and known. That is, as long as the engine is operated and maintained according to the factory documents,  the failure modes are known and happens so seldom that the risk is acceptable. The risk of sudden catastrophic failure of the engine parts (considering everything else is OK) is non existent from a practical point of view. When exceeding the TBO, the wear and tear on the engine starts to affect the reliability and any number of random things may happen at any time.

A TBO assures the engine will be reliable within its TBO, with a predetermined and very specific set of maintenance. With no TBO the engine can also be just as reliable, theoretically, but you have no idea what kind of maintenance is needed, or how often you have to do it. With no TBO, it runs "on condition". For a Lycoming this is OK for a limited time because the large number of engines in operation has limited the things to look for to a few points during condition inspection. For an engine that is put together by random aftermarket auto parts with no track of the origin, you have no idea, literally. You have no idea what to look for, thus no idea how to maintain it to assure it will run without failure the next hour.

So, an engine with a TBO is a world of difference better than an engine with no TBO, anyone saying differently don't know what they are talking about. It is better because you know how to maintain it, you know what to maintain and you know when to maintain it to be sure it will run without problems the next hours.

For practical purposes this means that a VW engine wizard will have no problems operating and running a VW aero engine conversion, and it will be every bit as reliable as a Lycoming. He knows what to look for, he knows what parts are OK, which aftermarket manufacturers are OK, how long each part last and so on. He will always be one step ahead of any failure waiting to happen. Myself, I am no VW engine wizard, I am no [any engine] engine wizard. So the only way for me to achieve a reliable engine is an engine with a TBO and a specific maintenance schedule within that TBO.