Ben Haas www.haaspowerair.com =20 -------------------------------------------------------------------------= ----- To: flyrotary@lancaironline.net Date: Wed, 27 Jul 2011 16:27:51 -0500 From: msteitle@gmail.com Subject: [FlyRotary] Kitplanes Article - Safety is no Accident There was an article in the February 2011 issue of Kitplanes titled, = "Safety is no Accident", by Ron Wanttaja. In light of the recent = flexplate failures, I found it interesting that it highlights two areas = where automotive engines tend to fail, the cooling system and the gear = reduction unit. To quote, "Note that auto conversions have a higher = accident rate right where you would expect it--in engine cooling and in = the systems that convert engine power to a slower speed for a propeller = or helicopter rotor." Seems that we've hit on one of the primary = failure modes here. According to Ron's calculations, the accident rate = for auto engine homebuilts was 23% higher than for homebuilts with = traditional engines. The rotary had the fewest total accidents, but the = rotary also has the fewest number of a/c flying. This is a well written = article that should be on everyone's reading list. =20 Note: Mr. Wanttaja is a systems engineer, engaged in satellite = orbit/constellation design and analysis, launch vehicle and onboard = propulsion system trades, and operations concepts for space systems. He = worked on the early design studies for the International Space Station. = Mark=20 ------=_NextPart_000_0026_01CC4D0B.4D91C6C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Since I'm involved in the design of a gearbox at = present,=20 I just thought I'd add that this is non-trivial to do properly. The = lawyers at=20 the gear manufacturer have made it impossible to use their design data, = unless=20 you are designing stationary equipment (HEAVY!!). This means testing is = required=20 to get accurate life data for each particular application. The problem = is, to=20 have statistically meaningful data you will have to test at least 10 = articles.=20 This is very expensive. Not something that a guy in his garage can = afford to do=20 properly. If you have statistical design data...you don't give it out. = So....the=20 best bet is to use something the airboat guys use successfully, or = something=20 people are currently flying successfully.

The flexplate failure looks like typical = high cycle=20 fatigue. Since these are used parts, we don't know the=20 part history. It could have been installed improperly in the car or = had a=20 manufacturing defect. The fact that two people have experienced failures = may be=20 a trend, maybe not.

1.) Inspect all flex plates very carefully = before=20 installation. Magnaflux/Dye penetrant, etc.

2.) Replace the rubber dampers at = annual

3.) Do regular Flexplate = inspections.

4.) Use a new flex plate if possible. =

If people continue to have failures, then = it's time=20 for redesign, but I wouldn't say that just yet. The two failures were = relatively=20 high power installations.

Monty

----- Original Message -----

From:=20 ben = haas=20

To: Rotary motors in = aircraft

Sent: Thursday, July 28, 2011 = 9:21=20 AM

Subject: [FlyRotary] Re: = Kitplanes=20 Article - Safety is no Accident

Great article for sure.....

The = introduction picture=20 is kool too. <GG>

Ben = Haas
www.haaspowerair.com
<= BR>

To: flyrotary@lancaironline.net
Date:=20 Wed, 27 Jul 2011 16:27:51 -0500
From: msteitle@gmail.com
Subject:=20 [FlyRotary] Kitplanes Article - Safety is no Accident

There was an article in the February 2011 issue of Kitplanes = titled,=20 "Safety is no Accident", by Ron Wanttaja. In light of the=20 recent flexplate failures, I found it interesting that it = highlights=20 two areas where automotive engines tend to fail, the cooling = system and=20 the gear reduction unit. To quote, "Note that auto = conversions have=20 a higher accident rate right where you would expect it--in engine = cooling and=20 in the systems that convert engine power to a slower speed for a = propeller or=20 helicopter rotor." Seems that we've hit on one of = the=20 primary failure modes here. According to Ron's = calculations, the=20 accident rate for auto engine homebuilts was 23% higher = than=20 for homebuilts with traditional engines. The rotary had the = fewest total=20 accidents, but the rotary also has the fewest number of a/c = flying. This=20 is a well written article that should be on everyone's reading=20 list.

Note: Mr. Wanttaja is a systems engineer, engaged in = satellite=20 orbit/constellation design and analysis, launch vehicle and onboard = propulsion=20 system trades, and operations concepts for space systems. He = worked on=20 the early design studies for the International Space Station. =

Mark

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