# Why isn't the push/pull twin more popular ? What you say.

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#### Turd Ferguson

##### Well-Known Member
Supporting Member
Beech morphed the B95 TravelAir into the 95-55 Baron the same year the Skymaster was introduced. (You can bet there was industrial spying in those days, lol). The new “Baron“ had Cont. 470’s with 260 hp and 4/5 seats like the Travel Air.
About the same time Piper was morphing the Apache into the Aztec, Piper’s the twin engine six, later named Seneca was still several yrs away.

#### Cardmarc

##### Well-Known Member
All P337’s have turbos. I flew a G model from TX to CA at 16,000’-very nice ride.

#### Air Trikes

##### Well-Known Member
Some of the PSRUs for the BMW opposed twins used a sprag clutch of some type. I recall reading that the prop windmilled and significantly affected glide performance. Good, I guess, if you want a steep glide angle, otherwise not so handy.
Most engines with SPG gearboxes don't spin propellers when switched off, unless a centrifugal clutch used. More info Air Trikes: Engines and Conversion Kits.

#### JML678

##### Member
Increasing use of BRS-style whole-airframe-carrying parachutes also detract from the need for a second engine.

#### Vigilant1

##### Well-Known Member
Supporting Member
Increasing use of BRS-style whole-airframe-carrying parachutes also detract from the need for a second engine.
That's true, if re-using the airplane isn't a significant priority.

#### PMD

##### Well-Known Member
Increasing use of BRS-style whole-airframe-carrying parachutes also detract from the need for a second engine.
The plus is that you will likely survive the resulting crash with minor injuries. The negative is that in a multi, you can simply complete the flight. Think about that while over Hudson Bay at night on a 50/50/100 day (50 knot wind, 50 feet vis and 100% rel humidity) on a nice -40C December flight. You wouldn't last more than a few minutes in that water wherreas in an Arctic winter (surface density altitude near -5000 ft.), even the most feeble twin (i.e. Pa23-150) could carry on with no big effort.

#### aeromomentum

##### Well-Known Member
The Diamond D40 without a BRS has an accident and fatality rate that is much lower than the very similar performance Cirrus SR20 with a BRS.

#### PMD

##### Well-Known Member
The Diamond D40 without a BRS has an accident and fatality rate that is much lower than the very similar performance Cirrus SR20 with a BRS.
Yeah, there is a huge level of concern that pilots thinking the BRS is a "get out of jail free" card tend to take more risks than those who are more conscious of the managing risks on flight.

#### tspear

##### Well-Known Member
Supporting Member
The Diamond D40 without a BRS has an accident and fatality rate that is much lower than the very similar performance Cirrus SR20 with a BRS.
That is often a quoted statistic. And very misleading.
With the super majority of accidents caused by the pilot, there is not enough data for statistical basis when comparing like missions and usages.

Tim

#### Mark Z

##### Well-Known Member
Good friend flying a 337 lost the rear one crossing the pond. Watching his track and communicating on text. He had the Icelandic helicopters leading him up a fiord to the airport.

#### Riggerrob

##### Well-Known Member
" ... , there is not enough data for statistical basis when comparing like missions and usages.

Tim"
Last time I heard that in court, I quickly compiled a list of 14 similar airplanes that crashed during a less-then-2-year period. Results were published on www.dropzone.com, but my lazy lawyer forgot to tell the judge.
GRRRRRRRR!
Did I ever tell you how much I admire and respect lawyers and how much I want to become a lawyer when I grow up?
Hah!
Hah!

#### tspear

##### Well-Known Member
Supporting Member
@Riggerrob

In those 14 accidents, how many were caused by the pilot, how many by mechanical systems, and how many while attempting to land a broken plane?
Overall, I would say, you did not provide enough context or information to intelligently reply.

I have had the discussion on Cirrus/Chute versus Diamond versus twin on multiple forums; with such people as Rick Beach. The reality is, there just is not enough "good" data to make comparisons really useful unless you make assumptions which drive your preconceived ideas. Oh, very few of us would want the invasive monitoring to gather "good data".

Tim

#### Riggerrob

##### Well-Known Member
@Riggerrob

In those 14 accidents, how many were caused by the pilot, how many by mechanical systems, and how many while attempting to land a broken plane?
Overall, I would say, you did not provide enough context or information to intelligently reply.
...

Tim
The lawsuit started with an accident when a Beechcraft King Air jump-plane suffered a fuel pump failure. The subsequent poorly-flown forced landing injured everyone on board.
Most of the other jump-plane accidents were caused by engine failure shortly after takeoff. Most engine failures occurred so low that the pilot was never going to make it back to a runway, so they landed in farmers' fields. A few of those rough-field landings ripped off landing gear while a couple more planes flipped onto their roofs. One pilot did a poor precautionary landing after he noticed high engine oil temperatures, shortly after take-off.
Only one accident can be blamed purely on pilot error, because the pilot forgot to lower flaps before take-off and aborted too late. His subsequent hard landing punched the main landing gear legs up through the wing!
My reason for publishing that summary of 14 accidents was to call "^%$#@!" on that arrogant lawyer's claim about not enough data. #### billyvray ##### Well-Known Member Here's you a push/pull. An ov-10 bronco/ COIN project concept. And for good measure, a biplane and tandem wing version... #### tspear ##### Well-Known Member Supporting Member The lawsuit started with an accident when a Beechcraft King Air jump-plane suffered a fuel pump failure. The subsequent poorly-flown forced landing injured everyone on board. Most of the other jump-plane accidents were caused by engine failure shortly after takeoff. Most engine failures occurred so low that the pilot was never going to make it back to a runway, so they landed in farmers' fields. A few of those rough-field landings ripped off landing gear while a couple more planes flipped onto their roofs. One pilot did a poor precautionary landing after he noticed high engine oil temperatures, shortly after take-off. Only one accident can be blamed purely on pilot error, because the pilot forgot to lower flaps before take-off and aborted too late. His subsequent hard landing punched the main landing gear legs up through the wing! My reason for publishing that summary of 14 accidents was to call "^%$#@!" on that arrogant lawyer's claim about not enough data.

Depending on what you want to claim, there may or may not be enough data. e.g. what is the failure rate of fuel pumps across the KA fleet?
Is the problem endemic to jump planes? Where all the engine failures the same? What altitude (matters if you claim the chute could have or have not affected the outcome)?

This is my point. Claims that Diamond DA-40 is safer than Cirrus; usually based on looking at the fatality rate of the DA-40 versus the SR-22; since the SR-22 is dominate. A just as logical comparison would be to look at the C152 against the Beech Baron.

Tim

#### Riggerrob

##### Well-Known Member
Depending on what you want to claim, there may or may not be enough data. e.g. what is the failure rate of fuel pumps across the KA fleet?
Is the problem endemic to jump planes? Where all the engine failures the same? What altitude (matters if you claim the chute could have or have not affected the outcome)?

This is my point. Claims that Diamond DA-40 is safer than Cirrus; usually based on looking at the fatality rate of the DA-40 versus the SR-22; since the SR-22 is dominate. A just as logical comparison would be to look at the C152 against the Beech Baron.

Tim
The engines in those 14 crashed jump-planes ranged from the usual Continentals and Lycomings installed in single-engined Cessnas, a bunch of Pratt & Whitney PT6A turboprops, a Walter turboprop (pretty much a communist copy of a PT6A and finally a Shvetsov ASh-61IR radial engine (communist copy of Wright R-1820 radial engine).

King Air have a known problem with fuel pump splines and Beechcraft issued a Service Bulletin requiring frequent inspections of fuel pump drive splines installed on that particular version of Pratt & Whitney PT6A engine. The A&P who last inspected that King Air did the inspection on one fuel pump, but ignored the fuel pump on the other side. Maintenance logs were "blurred" concluded the judge.

Since King Air jump-planes are used much harder than corporate KAs, Beechcraft issued a directive saying that jump-planes are not allowed to operate "on condition." A typical KA jump-plane does 3 or 4 landings per hour instead of the 3 or 4 per day for corporate KAs. The engines in that KA were a few thousand hours beyond Beechcraft's maintenance schedule.
Cessna issued a similar SB for Model 208 Caravans, but the inspection schedule is tighter, considering that Caravans only have a single engine.
Poor maintenance is endemic to jump-planes because they tend to be old, barley one step ahead of the scrap man. They wore out flying military, corporate executives, charters, sight-seers, freight, midnight mail, etc. before they start flying jumpers. Most skydiving centers operate on tiny profit margins, so aircraft maintenance tends be late on management's priority list.

Whether or not parachutes might have made a difference is complicated by the fact that BRS has never been certified for airplanes as heavy or as fast as King Airs. So the question devolves to the types of parachutes worn by individual skydivers. Only the solo jumper - who was closest to the door - had a chance of exiting and saving himself with his skydiving parachute. Only one of the tandem pairs had started to hook up his student. I usually wait until we climb above 5,000 feet before clipping on my student. I had just started the hook-up process when an engine started making weird noises. I looked at the distance to the door, considered the difficulty of carrying my student to the door, watched my altimeter unwind faster than I have ever seen an altimeter unwind before and concluded that a tandem pair could not exit in time.

#### dog

##### Well-Known Member
The engines in those 14 crashed jump-planes ranged from the usual Continentals and Lycomings installed in single-engined Cessnas, a bunch of Pratt & Whitney PT6A turboprops, a Walter turboprop (pretty much a communist copy of a PT6A and finally a Shvetsov ASh-61IR radial engine (communist copy of Wright R-1820 radial engine).

King Air have a known problem with fuel pump splines and Beechcraft issued a Service Bulletin requiring frequent inspections of fuel pump drive splines installed on that particular version of Pratt & Whitney PT6A engine. The A&P who last inspected that King Air did the inspection on one fuel pump, but ignored the fuel pump on the other side. Maintenance logs were "blurred" concluded the judge.

Since King Air jump-planes are used much harder than corporate KAs, Beechcraft issued a directive saying that jump-planes are not allowed to operate "on condition." A typical KA jump-plane does 3 or 4 landings per hour instead of the 3 or 4 per day for corporate KAs. The engines in that KA were a few thousand hours beyond Beechcraft's maintenance schedule.
Cessna issued a similar SB for Model 208 Caravans, but the inspection schedule is tighter, considering that Caravans only have a single engine.
Poor maintenance is endemic to jump-planes because they tend to be old, barley one step ahead of the scrap man. They wore out flying military, corporate executives, charters, sight-seers, freight, midnight mail, etc. before they start flying jumpers. Most skydiving centers operate on tiny profit margins, so aircraft maintenance tends be late on management's priority list.

Whether or not parachutes might have made a difference is complicated by the fact that BRS has never been certified for airplanes as heavy or as fast as King Airs. So the question devolves to the types of parachutes worn by individual skydivers. Only the solo jumper - who was closest to the door - had a chance of exiting and saving himself with his skydiving parachute. Only one of the tandem pairs had started to hook up his student. I usually wait until we climb above 5,000 feet before clipping on my student. I had just started the hook-up process when an engine started making weird noises. I looked at the distance to the door, considered the difficulty of carrying my student to the door, watched my altimeter unwind faster than I have ever seen an altimeter unwind before and concluded that a tandem pair could not exit in time.
well there you go,it's true
no one jumps out of a perfectly good airplane

#### PMD

##### Well-Known Member
That's true, if CONTINUING to use the airplane isn't a significant priority.
There, fixed that for you.

#### aeromomentum

##### Well-Known Member
When I was looking at both Cirrus SR20s and Diamond DA40's (same hull value, etc) I got insurance quotes for both. The insurance cost for the SR20 was over 3 times as high so it seems that all of the insurance companies seem to think the SR20 has 3 times the risk as a DA40. I did not look at SR22's. Plus the added BRS maintenance costs made the SR20 much more expensive to operate/own.

Now someone should compare the accident rates for the C337 and the C310.

Sometimes ideas work better for marketing than for use.