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I agree with what you have said but the crash data for 336/337 is no  
better than other twins.
Thomas A. Sult, MD
IntegraCare Clinic
www.icareclinics.com
tsult@charter.net



On Aug 2, 2009, at 3:58 PM, Greg R. wrote:

>
> Not to speak for Gary, but the pusher/puller configuration has  
> what's called
> "centerline thrust" - i.e. if you lose an engine, the thrust vector  
> stays on
> the centerline - theoretically making the engine-out procedure  
> easier to
> handle (ditto for a single-engine, though the engine-out procedure  
> is a lot
> more cut-and-dried...  ;-)).
>
> Wing-mounted twins have a more-complicated engine-out procedure -  
> not only
> identifying the dead engine, securing/feathering it (also true of
> centerline-mounted engine configs), but also maintaining a slight  
> bank angle
> to compensate for the thrust imbalance caused by the dead engine.
>
> http://en.wikipedia.org/wiki/Critical_engine
>
> Not sure if the Vmc (minimum-controllable velocity) restrictions  
> would apply
> to A/C with centerline-mounted engines, that's probably a question  
> for Gary.
>
> --
> GregR
>
>
> ----- Original Message -----
> From: "Greg Rudzinski" 
> To: "NavList" 
> Sent: Sunday, August 02, 2009 12:16 PM
> Subject: [NavList 9297] Re: Bygrave and Chichester
>
>
>
> Gary,
>
> How would the Cessna 336/337 perform if one engine fails? Is there an
> advantage to a pusher puller configuration over a single or wing
> mounted twins?
>
> Greg
>
> On Aug 2, 11:18 am, Gary LaPook  wrote:
>> Well, I would agree with you Douglas, as judged from our  
>> perspective in
>> 2009, that Chichester may have been "reckless." But as judged from  
>> the
>> standards of aviation pioneers almost 80 years ago, I prefer the word
>> "bold." If you look at early pioneering efforts, Lindberg, Perry, Sir
>> John Franklin, Columbus etc., they all appear reckless as viewed  
>> through
>> our prism of time. But that is what pioneering is all about, taking
> chances.
>>
>> Regarding you preference for twin engine flying, the accident  
>> statistics
>> show that they are more dangerous than singles, pretty
>> counter-intuitive. Flying a twin when both engines are operating is  
>> just
>> like flying a single, it only gets interesting when one quits. Then  
>> the
>> pilot must deal with a greatly reduced performance envelope and
>> asymmetric thrust causing control difficulties. If the pilot  
>> doesn't do
>> everything exactly right he ends up crashing and the crash happens  
>> at a
>> higher speed than would have occurred in a single. By US  
>> certification
>> standards (I expect they are similar in Britain) a single must have a
>> stall speed below 60 knots while a twin can have a much higher speed.
>> This means that a pilot trying to crash land a twin must fly above  
>> the
>> stall speed resulting in a higher impact speed and much more kinetic
>> energy to dissipate (varies with velocity squared), can we say "torn
>> aluminum" and "mangled bodies?" I've litigated airplane crashes for  
>> the
>> last twenty years and I have seen my share of bent aluminum and  
>> autopsy
>> photos. (BTW, a Cessna 310 Twin fits in a box on a standard pallet,
>> about five feet square and three feet deep after it impacts the dirt.
>> Airplanes are mostly air surrounded by an aluminum skin, just like an
>> empty beer can and they squish just like a beer can..)
>>
>> After the loss of one engine the airplane has little or no climb
>> capability. It will only climb or maintain altitude if the pilot does
>> everything right. If he doesn't get rid or the drag form the flaps,  
>> the
>> landing gear and the windmilling propeller immediately then he is  
>> going
>> down.
>>
>> I'll give you some examples. About seven years ago a Cessna 310 was
>> taking off from Laverne airport just northeast of Los Angeles on July
>> 4, 2002, Independence Day. One engine quit right after takeoff and  
>> the
>> pilot did not do everything right and the plane crashed on top of a
>> bunch of picnickers celebrating Independence Day in the park near the
>> airport resulting in the deaths of the two occupants of the plane,  
>> two
>> deaths of the picnickers and severe injuries for nine other people on
>> the ground. See the accident report at:
> http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX01FA152&rpt=fa
>>
>> The left propeller control was found "one inch aft." In order to  
>> feather
>> the propeller it is necessary to pull the prop control all the way  
>> aft,
>> about eight inches. Since the pilot did not move the prop control all
>> the way aft the prop did not feather and the plane could not maintain
>> altitude with the left engine windmilling creating a lot of drag. It
>> turned out that the pilot had done exactly as he had been instructed.
>> His instructor's technique for practicing engine out emergencies  
>> called
>> for the student pilot to just pull the prop control back one inch to
>> demonstrate that he had identified the failed engine and that he  
>> would
>> have feathered the prop in a real emergency. But in a high stress
>> situation people do what they have practiced so four dead people,
>> including two little children, and nine serous injuries.
>>
>> Another case I worked on involved a Piper Navaho hauling sight seers
>> around Hawaii. One engine packed it in and because the mechanic had  
>> not
>> used the proper method to adjust the wastegate controller on the  
>> other
>> engine, the remaining engine was not developing full power so the
>> airplane could not maintain altitude on the one engine. So even  
>> though
>> the pilot was doing everything right he still had to ditch in the sea
>> near Hilo and one little old lady, celebrating her fortieth wedding
>> anniversary, rode the plane to the bottom of the sea. See report
>> at:http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX00FA310&rpt=fa
>>
>> Another case I worked on involved a Twin Otter powered by two Pratt &
>> Whitney turboprop engines. The underground fuel tank from which the
>> airplane had just been refueled was contaminated with water (it  
>> looked
>> like mud) and one engine stopped right after the nose was raised  
>> due to
>> ingesting the water. The pilot then did everything wrong and  
>> feathered
>> the wrong engine, shutting down the one operating engine. This  
>> resulted
>> in 16 deaths of the occupants.
>> See:http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX93FA149&rpt=fa
>>
>> Having two engines gives one the sense that he has redundant  
>> systems and
>> that it is unlikely to have two reliable systems fail at the same  
>> time.
>> So, if an engine should fail once every 5,000 hours then the chance  
>> of
>> two such engines failing at the same time should be only once every
>> 25,000,000 (5,000 times 5,000) hours. But that assumes that the two
>> systems are completely independent from each other which is rarely  
>> the
>> case. First, obviously, both engines are being operated by the same
>> pilot and any error on his part can result in the loss of both  
>> engines.
>> Both engines received the same fuel so if one tank has contaminated  
>> fuel
>> they both do. They were refueled at the same time so if the pilot  
>> runs
>> one out of fuel then the other will follow moments later. The same
>> mechanic worked on both engine and if he screwed up one then he  
>> probably
>> screwed up the other one too. I remember watching a Cessna 310 take  
>> off
>> from Chicago Midway airport one day. Right after takeoff one engine
>> failed and the pilot was able to bring it around and land safely. The
>> plane taxied up to my hangar with one prop stopped and my friend Bill
>> jumped out and walked right past me. I asked him, as he passed,  
>> what had
>> happened and he said he couldn't stop to talk as he had to "go and  
>> clean
>> out his shorts." I don't think he was talking figuratively since he  
>> went
>> immediately into the men's room. The next day when I saw him I asked
>> again and he said he was doing a test flight after the mechanic had
>> adjusted the propeller governor and right after takeoff that one
>> propeller had gone into feather uncommanded which resulted in the  
>> loss
>> of power from that engine. As he was bringing the plane around to  
>> land
>> he said that all he could think about was that the mechanic had just
>> adjusted _both_ propeller governors and he was waiting for the  
>> other one
>> to go into feather too.
>>
>> In the case of over water ferry flights on which the plane is heavily
>> overloaded with fuel, the single engine ceiling may be below sea  
>> level.
>> This means with such a heavy load that the plane cannot maintain
>> altitude if just one engine fails and a ditching is inevitable. In  
>> this
>> case a twin is quite a bit less safe than a single since with two
>> engines you have twice the probability of an engine failure, 2 per  
>> 5,000
>> hours using my prior example.
>>
>> gl
>>
>> douglas.de...@btopenworld.com wrote:
>>> My interest in the Bygrave helical slide rule too Gary, was  
>>> stimulated
> when I read Chichester's book 'The Lonely Sea and the Sky' many  
> years ago.
>>
>>> I have been hoping ever since to find one, perhaps one of them would
> turn up in an antique shop or 'car boot sale', but now realise that  
> fond
> dream is far from ever becoming a reality.
>>
>>> It is very strange that they are now so incredibly rare  
>>> considering they
> must have been made in reasonably large numbers from the early  
> 1920's up to
> the mid 1930's, and were also an official piece of navigating 'kit'  
> for
> aircraft navigators in that period for the RAF, so must have been  
> made in
> fairly large numbers rather than just a relatively few for  
> experimental
> purposes. They were also available to buy privately. So what  
> happened to
> them all? It's most odd.
>>> Even the most arcane scientific apparatus and instruments are  
>>> usually
> preserved or survive in private hands to be sold on or given away to  
> others
> rather than just binned.
>>
>>> Are all those RAF Bygrave slide rules still locked away in some old,
> musty, forgotten RAF or government store at the back of dusty shelves
> awaiting some storekeeper to find them and be told to put them in an  
> auction
> of ex-government surplus. (Still dreaming you see !).
>>
>>> Whilst the skill and amazing endeavour of what Chichester achieved  
>>> is
> not to be denied an any way, (and you have now confirmed by your own
> practical flying test in a Tiger Moth); which was immediately  
> apparent to me
> when I read of the exploit, and it has continued to amaze me still -  
> with
> what he wrote I was also filled with the astonishment and feelings  
> that
> Chichester was idiotically reckless in what he did,..(I think) to  
> the point
> of insanity.
>>
>>> Given that he writes in a style which is deliberately meant to  
>>> make his
> story not just interesting but no doubt boost his (Chichester's)  
> reputation,
> and sales of the book, and hopefully have the reader clutching the  
> book with
> white knuckles in anticipation of events unfolding; nevertheless, he  
> exposes
> a devil-may-care attitude of quite serious stupidity and ignores  
> issues of
> high importance which any right-thinking person would not consider
> reasonable, and certainly not anyone who knows anything about flying  
> and the
> consequences involved in flying solo in a single engined aitrcraft  
> with a
> 'dodgy' engine over large stretches of water.
>>> ----------
>>
>>> I had a personal friend who taught me to fly, he was the Chief  
>>> Flying
> Instructor at Bembridge flying school, and who very nearly lost his  
> life
> when the donkey of the Cessna 150 stopped en route, mid - Solent, as  
> he was
> flying back to Bembridge from Goodwood, (The Solent is the sea -  
> only four
> miles of water between the Isle of Wight and the mainland) -and after
> turning downwind towards the mainland to maximise his ground  
> traverse, he
> did not make it and was...
>>
>> read more �
>
>
>
> >


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