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I did the majority of my PPL training in a PA28 Warrior and I've recently started transitioning over to a C172 and one thing that amazes me is how convenient it is to have a door either side of the aircraft.

My question is: Why does the PA28 only have one door on the passenger side of the aircraft?

I've never seen the schematics of a PA28 but my assumption might be that there's equipment that runs down the left side of the fuselage preventing a door from being added.

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    $\begingroup$ I don't have a good answer for this and I'd love to have one! $\endgroup$ – GdD Feb 16 '18 at 12:43
  • $\begingroup$ Good question, and my one main criticism of an otherwise lovely aircraft. What's worse, is that it's the Pilot who doesn't get a door meaning your poor, nervous, first time passenger now has to climb in unaided and take "responsibility" (real or imagined) for closing the door. </rant> $\endgroup$ – Dan Feb 16 '18 at 14:42
  • $\begingroup$ The difference in door design also makes It a little quieter and less traumatizing for passengers. I can't count the number of times a door has popped open in a rental Cessna. Don't recall it ever happening in a Piper style door. $\endgroup$ – Brock Adams Feb 16 '18 at 21:35
  • $\begingroup$ This is pretty common with low-wing single engine GA aircraft $\endgroup$ – Steve Kuo Aug 21 '18 at 16:07
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Having one door is just a design preference which makes the aircraft simpler, and lighter to build.

There are many other light aircraft with only one door. Besides Piper, most Mooney, Beechcraft, and Bellanca aircraft only have one door. Even the high wing Cessna 195, 206, P210, 337, and low wing Cessna 310 and 340 have only one door.

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    $\begingroup$ Not a criticism, I would like to see some citations though. There's a lot of speculation out there. $\endgroup$ – GdD Feb 16 '18 at 15:44
  • $\begingroup$ Good observations but I was hoping for something with some citations like @GdD mentions. $\endgroup$ – BDLPPL Feb 16 '18 at 17:27
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    $\begingroup$ Ignoring the structural considerations, it seems to be common sense that if you put a door in you'll need hinges, door seals, latch mechanism, cost of cutting a giant hole in the metal and installing all the pieces, ongoing adjustment and safety inspections... $\endgroup$ – user71659 Feb 16 '18 at 18:28
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    $\begingroup$ @GdD, the Citation has two doors. $\endgroup$ – Mark Feb 17 '18 at 1:40
  • $\begingroup$ @Mark, "GdD" was referring to a citation as a reference to a published or unpublished source. I don't have any citations and I don't feel they are needed as it is very obvious that additional doors add add weight and complexity to any aircraft design. ALSO.... Cessna Citation's have ONE entry door and an emergency exit which really can't be called a door. $\endgroup$ – Mike Sowsun Feb 17 '18 at 14:31
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It reduces weight and increases the structural strength of the fuselage, particularly with the typical design of a low wing aircraft. Later low wing aircraft like the Cirrus make use of an internal crash rollcage in the dorsal spins of the fuselage which adds extra strength to accommodate the second door. Diamond uses a semi monocoque tub-like design with a single swing up canopy enclosure to facilitate ease of entrance and egress.

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Piper's early low wing plane history, the best info I have found has been this:

http://www.pilotfriend.com/aircraft%20performance/Piper/11.htm

In 1954, Bill Piper was looking for a design to compete with the Bonanza. The engineers at Piper were busy with other projects at the time, so Bill Piper asked his friend Al Mooney if Piper could buy the new Mooney MK-20 design that Mooney had not yet started producing. Al wouldn't sell the design, so Bill Piper asked Al Mooney to come up with a totally new design. Al submitted a design to Piper that was an all metal 4 place monocoque construction with retractable gear, a 180 HP Lycoming, and a stabilator in place of an elevator. The stabilator was a new design, an all flying horizontal tail.

The cabin size of Al Mooney's design was a bit small, so the engineers at Piper increased the cabin size and the first Prototype PA-24, N2024P, was created in 1956. As you can see in this photo, the trailing link landing gear on the prototype is not what we have on our Comanches. It is suspected that Bill Piper decided that the trailing link landing gear would be too complex and expensive, and in an effort to undercut the cost of the Bonanza, he decided on the straight tube oleo strut landing gear that all Comanches are equipped with. Although it is much more difficult to make a good landing with the straight oleo strut landing gear than with the trailing link gear, that decision by Bill Piper is why Comanche Pilots have skills much more superior and a highly qualified group of Pilots than the Bonanza and Mooney bunch!!

The second prototype PA-24-180 flew in 1957. The first production 180 was delivered in January of 1958. It cost $14,500. The 250 HP Lycoming was meanwhile being tested in the original prototype PA-24, and the first production 250 Comanche was delivered in April of 1958.

And from Wikipedia:

Piper PA-28 CherokeeI have

At the time of the Cherokee's introduction, Piper's primary single-engined, all-metal aircraft was the Piper PA-24 Comanche, a larger, faster aircraft with retractable landing gear and a constant-speed propeller. Karl Bergey,[12] Fred Weick and John Thorp designed the Cherokee as a less expensive alternative to the Comanche, with lower manufacturing and parts costs to compete with the Cessna 172, although some later Cherokees also featured retractable gear and constant-speed propellers.

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  • $\begingroup$ could you highlight the parts of those quotes that answer the question "Why does the PA28 only have one door?" $\endgroup$ – Federico Aug 21 '18 at 15:19
  • $\begingroup$ Thought that was obvious - because they were copying what other companies had already done. $\endgroup$ – CrossRoads Aug 21 '18 at 15:22
  • $\begingroup$ sorry, didn't mean that. yes, in a sense it is obvious, but it is still better to either highlight specific sentences or to provide a summary in the answer, particularly for such extensive use of quotes $\endgroup$ – Federico Aug 21 '18 at 15:23
  • $\begingroup$ One could also try this link to the history of the development of the Bonanza Model 35 airbum.com/articles/ArticleBonanzaGuide.html or this link to the Bonanza society bonanza.org $\endgroup$ – CrossRoads Aug 21 '18 at 15:46

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