CASA Proposes To Restrict Jabiru Engines

[jnmeade]

In a rather strong proposal, the Australian aviation agency CASA proposes to restrict the use of Jabiru engines due to what they consider an excessive number of failures. (They show some numbers comparing them to Rotax.) Students would not be allowed to fly them solo. Pilots couldn't carry passengers.

http://www.australianflying.com.au/news/casa-moves-to-restrict-jabiru-engine-operations

"Draft Consultation Document 1425 effectively bans the use of Jabiru-engine aeroplanes for carrying passengers and for solo student training.

The proposed restrictions also include a constraints on flying over populous areas and the need to placard the aircraft with operating limitations."

"Jabiru founder Rod Stiff was quick to condemn the regulator for proposing the action.

"CASA has based this on spurious statistics and the commercial gripes of a few," he said last Friday. "I have tried to build a strong and safe aircraft and I reluctantly boast that in 23 years of Jabiru flight no one has been killed or seriously injured as a result of my doing.

"Jabiru is the safest light sport aircraft in Australia."

RA-Aus has responded by admitting that Jabiru engines have a failure rate higher than that of Rotax, but believes owners and pilots should be left to make their own decisions about safety. A statement issued comments:"

There's more. It's not a long read and is interesting so don't rely only on the excerpts, which are just there to tease you.

 

[Jim Logajan]

Here are the percentages:

Continental Engines: 18%
Lycoming Engines: 16%
Auto-Engine Conversions (including VW): 38%
Jabiru: 22%
Rotax (all): 28%

122%

More engine failures than can be fit into conventional math! Time to go back to flying gliders....

Edit: EdFred beat me to it. Slow typist.

 

[Jim Logajan]

The percentages I posted are the percentage of engine-related failures FOR EACH ENGINE TYPE. Adding the percentages between types is meaningless. I could list five different engines, each with 100% of the accidents caused by the engine. The fact that that would add up to 500% is immaterial.

Note also, that this is NOT THE PERCENTAGE OF ENGINES OF THAT TYPE THAT CAUSE ACCIDENTS. Some people see that 38% for auto-engine conversions and say, "Wow, 38% of auto-engine aircraft crash!" That's not the case at all.

The percentage is of airplanes that *did* crash, not the overall fleet.

Let me know if I got your procedure correct or not:

(1) You start with a database of records describing crashes.
(2) For each engine type E:
(2.1) You extract only those records where E is mentioned. You find you have extracted D records.
(2.2) You examine the D records and count A records where a failure of engine type E was listed as a cause of the accident.
(2.3) If A is less than 50, you feel the sample size is too low to go to the final step. [Or maybe you meant if D is less than 50, don't process further.]
(2.4) You generate percentage P which you then post, where P = 100*A/D.

 

[Jim Logajan]

I was looking at my database again in regards to some of the additional questions, and found I'd messed up the extraction process. Should have known to use a brute force method rather than try some multiple cross-references.

The numbers for all are lower. The difference between Jabiru and Rotax 912 is less, but still has definite gap.

Continental 13.4%
Lycoming 11.9%
Auto Conversions 28.8%
Jabiru 16.9%
Rotax (all) 20.4%
Rotax 912 12.1%

One could conclude from the above that pilots who fly auto conversions make so few mistakes and have so few fuel exhaustion or weather problems that engine failures are the dominant cause of their accidents.

Obviously I'm little surprised to see engine failures accounting for such relatively large (in my opinion) percentages of accidents.