X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imf23aec.mail.bellsouth.net ([205.152.59.71] verified) by logan.com (CommuniGate Pro SMTP 5.0.6) with ESMTP id 928308 for flyrotary@lancaironline.net; Mon, 16 Jan 2006 08:16:56 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.71; envelope-from=atlasyts@bellsouth.net Received: from ibm66aec.bellsouth.net ([70.149.4.85]) by imf23aec.mail.bellsouth.net with ESMTP id <20060116131610.RTJU17810.imf23aec.mail.bellsouth.net@ibm66aec.bellsouth.net> for ; Mon, 16 Jan 2006 08:16:10 -0500 Received: from [192.168.0.100] (really [70.149.4.85]) by ibm66aec.bellsouth.net with ESMTP id <20060116131609.BWZD19353.ibm66aec.bellsouth.net@[192.168.0.100]> for ; Mon, 16 Jan 2006 08:16:09 -0500 Mime-Version: 1.0 (Apple Message framework v746.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-32-196398649 Message-Id: <7F27422E-C210-46F5-A4E9-C70D55D2B673@bellsouth.net> From: Bulent Aliev Subject: Re: [FlyRotary] Anatomy of an almost crash. Date: Mon, 16 Jan 2006 08:16:28 -0500 To: "Rotary motors in aircraft" X-Mailer: Apple Mail (2.746.2) --Apple-Mail-32-196398649 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed We are all glad you are OK Dave. Buly On Jan 16, 2006, at 1:54 AM, David Leonard wrote: > I had to set my RV-6 down on highway 395 near Bishop Tuesday, and > here is the story. Mostly things I could have done better, some > that I did right or otherwise got lucky. It is an RV6 tip up with a > turbocharged Mazda rotary engine. > > I took the RV up to Mammoth to ski for the weekend. When I returned > to the plane Sunday evening I discovered a small puddle of coolant > under the engine. I had some concerns about the cold as my > antifreeze had been recently diluted with water when I had to make > a field repair of a coolant leak but I neglected to replace the > antifreeze (big mistake #1). I estimated 25/75 antifreeze/water and > the temperatures were supposed to be in the low 20's overnight. > This I thought would be enough but I was not sure. The puddle of > coolant seemed to prove that overnight the temp got low enough to > freeze some coolant and crack something. > > > A quick look under the cowl failed to reveal the souce of the leak > other than it was not coming from the previously fixed coolant line > or anywhere other than the radiator itself. I didn't have time to > trouble shoot as I had to get home to be at work the next day. > > I was able to hitch a ride home in another aircraft, then drive > back up the following evening after work. When I arrived at the > airport at 10pm the temperature was 3 deg F. In order to prevent > any further damage, I added some anti freeze and ran the engine for > a while to circulate it. When I left the airport at 11:30 pm the > temperature was -3 deg. This is obviously colder than I had > expected and was probably responsible for the damage. The > temperature in town was 20 deg despite the fact that town is higher > in elevation. The only explanation I have for the extreme low temp > at the airport is temperature loss from sublimation of the vast > deep snow fields around the airport in the very dry air (just a > guess). > > I arrived at sun-up the next morning (temp again 4 deg at airport > but 19 in town) and got to work on fixing the leak. After several > engine runs I determined that the leak was indeed coming from > somewhere in the radiator. There did not seem to be any coolant in > the oil, but I identified and fixed an oil leak in the turbo oil > return line. Also, the engine breather tube (which vents down in > the gear leg) had frozen and was causing the turbo to burn oil. > That issue was fixed as well. > > In order to temporize the radiator leak I decided to use a can of > radiator stop-leak and switch coolant to Evan's NPG. NPG is a pure > propylene glycol coolant that has a very high boiling temp and can > therefore be run with little or no coolant system pressure. I > switched out the coolant, added the stop-leak, and changed to a 7 > psi radiator cap. The stop-leak appeared to do it's job as there > was no visible continued leak after an hour of running the engine > on the ground at fast idle with some brief runs at higher RPM. > > At about 2pm I was cold (temp at the airport now in the mid 20's) > and tired (had slept in the car overnight) but decided it was safe > to make the flight to Bishop - 27 miles away and 3000 feet lower. > There I would remove the cowl and give everything a good look. > Since the coolant leak had only lost about a quart in 3 days, was > now sealed and would be flown with low pressure I assumed the most > I could loose in the 15 min flight would be about a cup of coolant > (Big mistake #2?) > > The first 8 minutes of flight all systems were green. Then over the > course of a minute the coolant temp went up to over 280, oil temp > up to over 200 (the highest it has ever been). Being about half-way > I decided to continue to the lower Bishop airport. Then the > alternator quit (buss voltage dropped to 11.7 and battery showed a > discharge). Then oil pressure dropped to zero, followed shortly > after by the engine stopping to make power and a puff of smoke > coming in into the cockpit thought the heater vent (cowl air - not > a heat muff). > > It appeared as though I would be able to glide to the Bishop > airport. I was at 9000 feet. Bishop was 13 miles away at 4000 feet > with no significant winds. This distance is solidly within the > typical glide ratio of the RV6 so I calmly assumed there would be > an easy dead-stick onto the airport. > > I tried to get the prop to stop windmilling by slowing. In my > initial flight testing I had been able to stop the prop from > windmilling at about 80 kts. However, even by slowing to 65kts IAS > I was unable to stop the windmilling. It turns out that overheating > the engine had caused the loss of compression on all rotor faces > and this prevented me from stopping the windmilling. I was seeing > descent rates of 800-1000 fpm at 90 KIAS and it soon became > apparent that making the airport would be sketchy at best, so I > opted for a quality highway rather than try to overfly the town to > make the airfield. > > I was able to spot a section of Hwy 395 that was 4-lane divided (no > opposing traffic) that also seemed to be free of turns, power lines > and intersections. I relayed my situation to the Bishop unicom and > got a prompt response. I turned off my fuel pump and in accordance > with my training turned off the master power on short final... Doh! > I have all electric flight instruments and now had no time to re- > boot either of my 2 air speed indicators. > > My plan for traffic avoidance was to come in faster than typical > traffic speed, then bleed off that speed at 20 feet over the > highway. That way any traffic has plenty of time to see me and slow > down while I am bleeding off speed. Touchdown was uneventful and > quite a relief. No injury or damage. > > The Bishop police were there within minutes, and 2 hours later the > plane was tied down at the Bishop airport. I had no time or desire > to remove the cowl so the cause is still very unclear. A loss of > the accessory belt would explain both the inability to cool and the > loss of the alternator, but my bet is still on something to do with > the extreme cold and radiator leak. I have to shamefully admit that > time pressures were a contributing factor. Feeling the need to > return home, I probably rushed the testing process after making > repairs. I should have circled Mammoth airport in order to test the > repairs at high power before attempting continued flight, > especially in mountainous terrain (though there is no freeway in > SoCal that would be as forgiving as that section of 395). > > I plan to rent some kind of truck next weekend and drive up, remove > the wings, and bring the plane home. It will remain in our garage > for the next 8 months while I deploy to Iraq. (Suggestions or > offers for use of an adequate truck or trailer would be much > appreciated). This will also give me a chance to paint the plane > and do a lot of the finishing touches that will be easier to do at > home than at the airport. Obviously I will need to rebuild the > engine as well, but that is a relatively minor issue. > > This was quite a learning experience I obviously hope I never have > to repeat. All things considered, I feel quite lucky that things > turned out so well. > > Lastly, I want to thank the Bishop Unicom, Police Dept, Highway > Patrol, Cal Trans, and Fire Department who were all very > professional and helpful. Also, thank you to the fellow RV6 owner > was passing by and took an hour and a half out of his day to drive > back up to Mammoth and get my car for me. > > > > -- > Dave Leonard > Turbo Rotary RV-6 N4VY > http://members.aol.com/_ht_a/rotaryroster/index.html > http://members.aol.com/_ht_a/vp4skydoc/index.html --Apple-Mail-32-196398649 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=US-ASCII
We are all glad you = are OK Dave.
 =
Buly

On Jan 16, 2006, at 1:54 AM, David = Leonard wrote:

I had to set my RV-6 down on highway 395 near Bishop = Tuesday, and here is the story. Mostly things I could have done better, = some that I did right or otherwise got lucky. It is an RV6 tip up with a = turbocharged Mazda rotary engine.

I took the RV up to Mammoth to = ski for the weekend. When I returned to the plane Sunday evening I = discovered a small puddle of coolant under the engine. I had some = concerns about the cold as my antifreeze had been recently diluted with = water when I had to make a field repair of a coolant leak but I = neglected to replace the antifreeze (big mistake #1). I estimated 25/75 = antifreeze/water and the temperatures were supposed to be in the low = 20's overnight. This I thought would be enough but I was not sure. The = puddle of coolant seemed to prove that overnight the temp got low enough = to freeze some coolant and crack something.


A quick look under the cowl = failed to reveal the souce of the leak other than it was not coming from = the previously fixed coolant line or anywhere other than the radiator = itself. I didn't have time to trouble shoot as I had to get home to be = at work the next day.

I was able to hitch a ride home in another = aircraft, then drive back up the following evening after work. When I = arrived at the airport at 10pm the temperature was 3 deg F. In order to = prevent any further damage, I added some anti freeze and ran the engine = for a while to circulate it. When I left the airport at 11:30 pm the = temperature was -3 deg. This is obviously colder than I had expected and = was probably responsible for the damage. The temperature in town was 20 = deg despite the fact that town is higher in elevation. The only = explanation I have for the extreme low temp at the airport is = temperature loss from sublimation of the vast deep snow fields around = the airport in the very dry air (just a guess).

I arrived at = sun-up the next morning (temp again 4 deg at airport but 19 in town) and = got to work on fixing the leak. After several engine runs I determined = that the leak was indeed coming from somewhere in the radiator. There = did not seem to be any coolant in the oil, but I identified and fixed an = oil leak in the turbo oil return line. Also, the engine breather tube = (which vents down in the gear leg) had frozen and was causing the turbo = to burn oil. That issue was fixed as well.

In order to temporize = the radiator leak I decided to use a can of radiator stop-leak and = switch coolant to Evan's NPG. NPG is a pure propylene glycol coolant = that has a very high boiling temp and can therefore be run with little = or no coolant system pressure. I switched out the coolant, added the = stop-leak, and changed to a 7 psi radiator cap. The stop-leak appeared = to do it's job as there was no visible continued leak after an hour of = running the engine on the ground at fast idle with some brief runs at = higher RPM.

At about 2pm I was cold (temp at the airport now in = the mid 20's) and tired (had slept in the car overnight) but decided it = was safe to make the flight to Bishop - 27 miles away and 3000 feet = lower. There I would remove the cowl and give everything a good look. = Since the coolant leak had only lost about a quart in 3 days, was now = sealed and would be flown with low pressure I assumed the most I could = loose in the 15 min flight would be about a cup of coolant (Big mistake = #2?)

The first 8 minutes of flight all systems were green. Then = over the course of a minute the coolant temp went up to over 280, oil = temp up to over 200 (the highest it has ever been). Being about half-way = I decided to continue to the lower Bishop airport. Then the alternator = quit (buss voltage dropped to 11.7 and battery showed a discharge). Then = oil pressure dropped to zero, followed shortly after by the engine = stopping to make power and a puff of smoke coming in into the cockpit = thought the heater vent (cowl air - not a heat muff).

It appeared = as though I would be able to glide to the Bishop airport. I was at 9000 = feet. Bishop was 13 miles away at 4000 feet with no significant winds. = This distance is solidly within the typical glide ratio of the RV6 so I = calmly assumed there would be an easy dead-stick onto the airport. =

I tried to get the prop to stop windmilling by slowing. In my = initial flight testing I had been able to stop the prop from windmilling = at about 80 kts. However, even by slowing to 65kts IAS I was unable to = stop the windmilling. It turns out that overheating the engine had = caused the loss of compression on all rotor faces and this prevented me = from stopping the windmilling. I was seeing descent rates of 800-1000 = fpm at 90 KIAS and it soon became apparent that making the airport would = be sketchy at best, so I opted for a quality highway rather than try to = overfly the town to make the airfield.

I was able to spot a = section of Hwy 395 that was 4-lane divided (no opposing traffic) that = also seemed to be free of turns, power lines and intersections. I = relayed my situation to the Bishop unicom and got a prompt response. I = turned off my fuel pump and in accordance with my training turned off = the master power on short final... Doh! I have all electric flight = instruments and now had no time to re-boot either of my 2 air speed = indicators.

My plan for traffic avoidance was to come in faster = than typical traffic speed, then bleed off that speed at 20 feet over = the highway. That way any traffic has plenty of time to see me and slow = down while I am bleeding off speed. Touchdown was uneventful and quite a = relief. No injury or damage.

The Bishop police were there within = minutes, and 2 hours later the plane was tied down at the Bishop = airport. I had no time or desire to remove the cowl so the cause is = still very unclear. A loss of the accessory belt would explain both the = inability to cool and the loss of the alternator, but my bet is still on = something to do with the extreme cold and radiator leak. I have to = shamefully admit that time pressures were a contributing factor. Feeling = the need to return home, I probably rushed the testing process after = making repairs. I should have circled Mammoth airport in order to test = the repairs at high power before attempting continued flight, especially = in mountainous terrain (though there is no freeway in SoCal that would = be as forgiving as that section of 395).

I plan to rent some kind = of truck next weekend and drive up, remove the wings, and bring the = plane home. It will remain in our garage for the next 8 months while I = deploy to Iraq. (Suggestions or offers for use of an adequate truck or = trailer would be much appreciated). This will also give me a chance to = paint the plane and do a lot of the finishing touches that will be = easier to do at home than at the airport. Obviously I will need to = rebuild the engine as well, but that is a relatively minor issue. =

This was quite a learning experience I obviously hope I never = have to repeat. All things considered, I feel quite lucky that things = turned out so well.

Lastly, I want to thank the Bishop Unicom, = Police Dept, Highway Patrol, Cal Trans, and Fire Department who were all = very professional and helpful. Also, thank you to the fellow RV6 owner = was passing by and took an hour and a half out of his day to drive back = up to Mammoth and get my car for me.



-- =
Dave Leonard
Turbo Rotary RV-6 N4VY
http://membe= rs.aol.com/_ht_a/rotaryroster/index.html
= http://members.aol.com/_ht_a/vp4skydoc/index.html
= --Apple-Mail-32-196398649--