Hello SonexBuilders.net,
On the morning of January 12, 2016, immediately after reading the final report issued at midnight on January 11th, I sent the following message to Jason Aguilera, Investigator In Charge (IIC) for this investigation:
Hello Jason,
I would like to formally object to the statement in the report’s “Analysis” section -- paragraph 2, sentence 5: “It could not be determined whether the turbocharger would not rotate due to impact damage or whether it seized in flight resulting in a partial loss of engine power.”
According to statements by Joe Norris, he reports that, with your oversight when examining the turbocharger before it was sent to the NTSB laboratory, the impact damaged portion of the turbocharger housing was removed, and the turbine shaft was found to be rotating freely once pressure from the impact-damaged section was removed from the turbine. Joe’s account of the initial turbocharger examination directly conflicts with the statement in Factual Report section “Wreckage and Impact Information” paragraph 5, stating that disassembly was halted after finding a crack in the housing, and this bears clarification. I’ve copied Joe on this email and would like for you both to communicate about the actual sequence of events.
Factual Report section “Tests and Research” paragraph 2 also states that “Both the compressor wheel and turbine wheel turned together freely within the center housing when either was rotated by hand.” This statement also conflicts with the mischaracterization of the “Analysis” section of the report, paragraph 2, sentence 5 as quoted above.
What is our process for clearing these items up in the report?
Thanks,
-Mark
Jason is taking the matter up with his management at NTSB to determine how to proceed.
The fact of the turbocharger’s free rotation after removal of the impact-damaged turbine housing was discussed at-length here at Sonex before the turbocharger ever came back from the NTSB lab, so we are certain that Joe’s account of the chain of events in the investigation per my message above is accurate. Also note that all parts from the accident aircraft were kept in a sterile chain of custody per NTSB procedures and Sonex Aircraft representatives were only able to access and examine these parts under the supervision of the NTSB, usually accompanied by FAA representatives as-well.
As Joe has remarked, the engine and turbocharger were fully disassembled and examined by Sonex aircraft and two NTSB investigators, along with two FAA representatives. The lack of physical evidence suggesting a root cause of the accident gives the NTSB and Sonex Aircraft no direction in-which to focus further investigative efforts. NOBODY wants to know what happened more than us. But unfortunately, that just isn’t possible to ascertain at this time. I can assure you that every theory and point of due diligence discussed in this thread, and more, have been pursued in this investigation. It's also worth noting that although Joe was the Sonex Aircraft lead for these efforts, John Monnett and other Sonex Aircraft staff members have been heavily involved throughout the process, including the disassembly and examination of the turbocharger, engine, and test stand running of the accident wastegate on our exemplar engine. There were many sets of eyes on these parts throughout the investigation. There's not one of us here that doesn't relive June 2nd 2015 on a daily basis, and that doesn't try to mentally put ourselves in that cockpit and divine missing pieces of the puzzle. That mental exercise will likely haunt us forever.
Aside from our formal objection to the investigation’s analysis details, as copied above, there’s nothing we can add to the NTSB final report, accident docket materials, or to this discussion thread that will satisfy many of you in this forum. As we have done for years with both airframes and engines via our existing service bulletin systems, all we can do going forward is to address issues that can be positively identified by physical evidence. While we believe strongly that there must have been a mechanical root cause to this accident, we have no data pointing to that cause, or to a condition that would threaten the worldwide fleet at-large.
As-difficult as it may be for many of you to accept, we cannot ignore the many thousands of successful fleet hours flown on AeroVee engines of all types, including AeroVee Turbo engines, flown around the globe before and since June 2, 2015. Our mission and our pledge is to continue offering and supporting the AeroVee product line actively, in the most responsible manner possible.
I know that many of you will say that, likewise, we cannot ignore two factory fleet accidents within 14 months’ time, however, we can only act upon data gleaned from the investigations of those accidents, and at this point, we have no data that supports action.
We would like to once again publicly thank Joe Norris for his work on this most difficult and frustrating of investigation processes as our designated representative to the NTSB, and for his willingness to respond to posts on this thread with his first-hand information about the facts and events of this investigation. Coming-up empty on this investigation pains each and every one of us and our families at Sonex Aircraft more than words can describe.
--
Mark Schaible
General Manager
Sonex Aircraft, LLC
phone: 920-231-8297
fax: 920-426-8333
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