X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [66.234.112.76] (HELO gctel.com) by logan.com (CommuniGate Pro SMTP 5.1.11) with SMTP id 2226052 for flyrotary@lancaironline.net; Wed, 01 Aug 2007 23:27:45 -0400 Received-SPF: none receiver=logan.com; client-ip=66.234.112.76; envelope-from=lerohl@gctel.net Received: from [69.42.226.140] (HELO D8HZVF21) by gctel.com (CommuniGate Pro SMTP 4.2.6) with SMTP id 61015611 for flyrotary@lancaironline.net; Wed, 01 Aug 2007 22:27:07 -0500 Message-ID: <008501c7d4b4$fdb7a020$6401a8c0@D8HZVF21> From: "Gaylen Lerohl" To: "Rotary motors in aircraft" Subject: Redundant systems Date: Wed, 1 Aug 2007 22:27:01 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0082_01C7D48B.149302F0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0082_01C7D48B.149302F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable A few weeks ago Ed Anderson reported a failed circuit breaker feeding = both coils. He urged that we make our systems redundant where possible, = with separate circuits and circuit protection to each. I second his = plea and share my recent experience as reinforcement. =20 I have about 60 flight hours and about 15 ground hours on my RV8. It is = powered by a 13B with the stock Mazda coils. Tracy recently updated my = EC2 and I installed it Saturday. After a half hour ground run adjusting = the MAP table I shut down and installed the cowl. Taking Tracy's advice = I took off, stayed near the airport and did the Mode 9 programming at = altitudes of 7,000' to 10,000' AGL. I did several simulated approaches = and landings at altitude enjoying the smoother running engine compared = with the previous iteration of the program. Also spent time among the = puffy clouds and cooler air above the haze layer! After 1.5 hours I = began simulating another approach but when I pulled the power to idle = the engine quit. Emergency procedures were fruitless. Even shutting = down the entire system and attempting a power-up didn't result in an = engine start. I was several miles from the field at about 7,000 AGL. I = set up an 85 KT glide, and decided to land on a runway with a six KT = tailwind to avoid flying over a residential area or over a lake on the = approach to an alternate runway. I arrived over the approach end of the = runway on a crosswind leg with 1500' to lose so I began a tight pattern = flying a descending left turn to lose altitude and position myself for = the landing. I lost 500 feet in the first 180 degrees and about the = same in the second 180 degrees. I rolled out on final high and hot, = shut off all the electrics, landed long but without incident. It all = went pretty well other than the fact I forgot to roll in flaps when I = could have used the drag to get me down sooner. =20 I use fuses for circuit protection so the first troubleshooting step was = to check the fuses - all were OK! I suspected the coils were involved = because the tachometer was reading zero even though the engine was = windmilling. The tach is driven by a signal from the trailing coil. = Using the new diagnostic features, the injectors were clicking OK but = there was no spark. Tracy reminded me of Ed Anderson's post about the = failed breaker feeding both coils. Upon close examination the fuse had = not blown but apparently it has been warm because it had warped. It was = in the fuse holder but somehow was not making contact. Replacing the = fuse cured the problem. =20 I am now a firm advocate of redundancy! I have added a circuit to power = the coils separately and plan to replace the essential bus fuse panel = with circuit breakers. I share this experience to urge those of you who = use a single circuit to power your coils, your fuel pumps, your EC2 or = any other critical systems to modify your wiring so a single circuit = failure doesn't place you in a dangerous position. Mine ran for about = 75 hours. It was just a stroke of good fortune that the failure = occurred while near the airport at an altitude higher than I usually = fly. =20 =20 Here are a couple of data points that may be of interest: The fixed pitch wood prop windmilled at a 100 KT glide, rate = of descent about 1000 FPM. The prop stopped at about 90 KT. Fly safe! Gaylen Lerohl RV8 Alexandria, Minnesota =20 =20 ------=_NextPart_000_0082_01C7D48B.149302F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

A few=20 weeks ago Ed Anderson reported a failed circuit breaker feeding both = coils.  He urged that we make our = systems=20 redundant where possible, with separate circuits and circuit protection = to=20 each.  I second his plea = and share=20 my recent experience as reinforcement.

 

I have=20 about 60 flight hours and about 15 ground hours on my RV8.  It is powered by a 13B with = the stock=20 Mazda coils.  = Tracy recently updated my = EC2 and=20 I installed it Saturday.  = After a=20 half hour ground run adjusting the MAP table I shut down and installed = the=20 cowl.  Taking=20 Tracy=92s advice I took off, = stayed=20 near the airport and did the Mode 9 programming at altitudes of 7,000=92 = to=20 10,000=92 AGL.  I did = several=20 simulated approaches and landings at altitude enjoying the smoother = running=20 engine compared with the previous iteration of the program.  Also spent time among the = puffy clouds=20 and cooler air above the haze layer! =20 After 1.5 hours I began simulating another approach but when I = pulled the=20 power to idle the engine quit. =20 Emergency procedures were fruitless.  Even shutting down the entire = system and=20 attempting a power-up didn=92t result in an engine start.  I was several miles from the = field at=20 about 7,000 AGL.  I set up = an 85 KT=20 glide, and decided to land on a runway with a six KT tailwind to avoid = flying=20 over a residential area or over a lake on the approach to an alternate=20 runway.  I arrived over = the approach=20 end of the runway on a crosswind leg with 1500=92 to lose so I began a = tight=20 pattern flying a descending left turn to lose altitude and position = myself for=20 the landing.  I lost 500 = feet in the=20 first 180 degrees and about the same in the second 180 degrees.  I rolled out on final high and = hot, shut=20 off all the electrics, landed long but without incident.  It all went pretty well other = than the=20 fact I forgot to roll in flaps when I could have used the drag to get me = down=20 sooner.

 

I use=20 fuses for circuit protection so the first troubleshooting step was to = check the=20 fuses =96 all were OK!  I = suspected=20 the coils were involved because the tachometer was reading zero even = though the=20 engine was windmilling.  = The tach is=20 driven by a signal from the trailing coil. =20 Using the new diagnostic features, =20 the injectors were clicking OK but there was no spark. =20 Tracy reminded me of = Ed=20 Anderson=92s post about the failed breaker feeding both coils.  Upon close examination the = fuse had not=20 blown but apparently it has been warm because it had warped.  It was in the fuse holder but = somehow=20 was not making contact.  = Replacing=20 the fuse cured the problem.

 

I=20 am now a firm advocate of redundancy! =20 I have added a circuit to power the coils separately and plan to = replace=20 the essential bus fuse panel with circuit breakers.  I share this experience to urge = those of=20 you who use a single circuit to power your coils, your fuel pumps, your = EC2 or=20 any other critical systems to modify your wiring so a single = circuit=20 failure doesn=92t place you in a dangerous position.  Mine ran for about 75 = hours.  It was just a stroke of good = fortune=20 that the failure occurred while near the airport at an altitude higher = than I=20 usually fly.  =

 

Here are=20 a couple of data points that may be of interest:

         =20 The fixed pitch wood prop windmilled at a 100 KT glide, rate of = descent=20 about 1000 FPM.

         =20 The prop stopped at about 90 KT.

 

Fly=20 safe!

Gaylen Lerohl

RV8

Alexandria, = Minnesota

 

 

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