View Full Version : Piper Navajo
13th Oct 2011, 08:03
Needing some information from anyone that has operated a Piper Navajo on charter, we are based in South Africa and have had conflicting information. Have been told that the Navajo cannot maintain on one engine with 6 passengers, incident in Mozambique where pilot lost the turbo on take off with 5 pax and had to do an emergency landing. If anyone has any stats on safety of Navajo would appreciate your feedback
13th Oct 2011, 08:09
is a joke.
2500 hrs on type, and several Cof A renewal flights, with demonstrated s/e climb.
Please do not expect a PA31 to climb on one engine, my procedure is, if slow, then close other engine to permit the crash to be carried out straight ahead.
If some airspeed, then the second engine permits the crash site to be determined, within a 1nm radius....
The C of A renewal, was always a cheat, and the climb performance adjusted to match the published performance. of a NEW aircraft.
DO NOT EXPECT A CLIMB.
13th Oct 2011, 10:22
Thanks for your feedback, really appreciate it.
13th Oct 2011, 13:06
I don't have the experience that the previous poster has, but for that type of a load, you can't do too much better than a Navajo, and whatever you do, don't buy a C-421.
13th Oct 2011, 15:28
No light twin certified under Part 23 has much performance on one engine. Unless, and until, configured for min. drag and flown correctly you can expect to go downhill. The Navajo is no worse than most others.
You can, however, improve its performance with the Panther upgrade. It replaces the stock 310 hp or 325 hp engines with a Chieftain's 350 hp versions. You can also add a VG kit which will allow a greater take-off weight (and still meet certification performance requirements) or use the slight additional performance at orignal weights as a bonus.
I would have expected a correctly flown PA31 at MTOW to fly OK with only a blown turbo. It would need to be flown correctly though. Also, are you sure it wasn't overloaded? 6 bums + lots of fuel will do that.
I had an inflight failure a couple of months ago in a Panther Navajo I manage when an injector line broke. I wasn't far off MTOW (4 POB, bags, fuel fuel - 1 hour). At 9000' I needed full power and precise technique with heat becoming an issue, 8000' climb power but heat management was a bit of a pain, and at 6000' 75% power with temps in normal range at Vyse+10-20
I wanted to burn fuel before configuring for landing to improve performance with gear & flap out so chose to airport hop back to home base with maintenance. There were some two dozen airports we flew past in the hour+ it took to return so we were never more than a few minutes from a landing point if necessary.
It really wasn't a drama at all.
13th Oct 2011, 15:45
Believe it or not, not all Navajos that were built had turbocharged engines. The first few years of manufacturing Piper made a 'Commuter' version of the Navajo with 300hp un-turbocharged engines.
It was an absolute pig. Forget performance on one engine, it had no performance with both engines. I don't know if there are any of those left around or not.
I had a good friend that lost an engine on a normal Navajo after takeoff. It quit about 2,500 AGL and he was around three miles from the airport when it quit. He made it to about a half mile to the runway and realized he was not going to make it to the runway and landed gear up it in on an open field. No one was injured. The aircraft was repaired and resumed operations.
Oh, he had five passengers and full fuel.
13th Oct 2011, 20:34
fantastic aircraft, good load, and pax loved it.
BUT it is a single......with two engines.
15th Oct 2011, 16:13
I deliberately ignored the normally aspirated 300hp original version. Not many of them around, thankfully, and not worth bothering with unless re-engined with turbos & more HP
17th Oct 2011, 16:24
I have about 1000 hrs on the Pressurized Navajo, may be the worst of all.
425 hp per engine but useless at heavy weights.
I used to rotate the aircraft at 95 kts, because the manual says to forget to expect any climb below that speed on one engine. So in the briefing i was always telling to my copilot that as long as we are on the ground (below 95 kts) we abort in case of engine failure, it didn't matter how long the remainig runway was
I also used to take off with the cowl flaps closed (except in very high temperature) beacause they were real speedbrakes
I flew Navajo a cuple of hours, an easy rule:
Big guys behind Captain and First Officer seat
All luggage inside nose compartment
Girs at the back
Place of CG it's really important in those type of aircraft
2nd Nov 2011, 16:43
I have about 1000 hrs on the Pressurized Navajo, may be the worst of all.
I figured if I was here on Pprune long enough I'd run into someone else that flew a Pressurized Navajo. I don't have as much time in them as you, but I was happy to stop flying them. We had a lot of engine problems until we started using 65% power for cruise, the engines seemed to like 65-70% much more than 75%. Not to mention the Micky Mouse pressure controller system.
There is one sitting at a local airport here, the tires and struts are flat, but it is providing a nice home for numerous birds.
I really don't believe that there any still flying, at least I have not seen one, except the one I described above, here in the US and I never saw one when I was flying around Europe. Or the rest of the world for that matter.
2nd Nov 2011, 18:29
cant speak for the PA31-325 Navajo, but over 1000hrs on its bigger sister PA31-350 Chieftain, what a lovely aircraft, flown for "old" Airlink, and when operated within W&B limitations would perform as per the AFM.
One of my fellow PA31 Capt's had a magneto shaft failure (common shaft supplying both magneto's) after take-off at JNB, with a full load, and he climbed out and flew it all the way to a single engine landing, with a full load of pax and baggage...at MAUW
critical was getting the "barn door" cowl flaps closed ASAP on the dead engine, and not flying even slightly overloaded, and as also mentioned the CofG must also be right.
I have just a few hours in what I remember as a PA-31-325CR. Anyway, it was a short-body machine with contra-rotating engines and it flew just fine on two engines. My check-out was cursory, so that I never got to practice much engine-out work, if any. (This was back in 1981, so that memory has faded.)
We had a guy who used to get in our hair when we were operating strictly legal with Twotters to Hilton Head , South Carolina. We needed VMC to descend and land at the VFR-only airport, so that we'd divert to Savannah when we were down to MEA and still in the soup. Mr Navajo Chieftain would report that he was in the clear, just a few miles off our position and go on in to land. That was either 'superior pilot technique' or else 'flagrant cheating,' when I could not possibly say which.
So nemesis in the form of an engine failure after take-off saw him plop his Navajo down in the parking lot of a Snake and Ale restaurant, when the only survivor was the guy riding in the right front seat. He couldn't remember how he made it out but everyone else burned up with the aircraft, when most were probably killed or at least knocked unconscious on impact by the way the fuselage squashes down and then springs back into shape. I never read the final report, when there were the usual 'pilot error' rumors, but it might have been simply that the thing just didn't want to fly on one with a full, or too-full load, either slightly mismanaged or else even properly flown.
Then another guy I knew, liked and respected bought himself a Navajo to upgrade his little air taxi operation. He lost one engine right after rotation from a short strip and came around in a losing right-turn argument with VMC until he finally hit a big tree and died.
Then there was a former colleague who landed a job with a proper airline back in the world. He was on a positioning flight in a C404 when one engine failed. I don't know what went wrong but, again, they crashed and our man died.
In fact, I can remember quite a few of those crashes where, on paper, a light twin should have flown just fine but didn't. Overloaded, underperforming, poorly flown... who can say, but I don't think any of those crashes were suicide! The U.S. Army operated a version of the Beech Baron 55, the T-42 (?), when they had quite a few 'engine failure after takeoff' crashes, so that one of their safety specialists, a Major I believe it was, wrote some S.O.P.s about how to fly the thing properly. Well, their expert died in one of those crashes!
Those are now, for the most part, old airplanes with engines that have their best days behind them, and, anyway, Part 23 doesn't require guaranteed performance in any case.
I used to look at the performance charts for the Cessna 404 I was operating in Nigeria at ISA +15° and more, and then subtract for gear and flaps down to see how big a negative number that made, which was food for thought. To operate an old airplane at its WAT limits and expect to get away with an engine failure is being optimistic. That's okay; I have nothing against optimism, especially when you need a job, but you might find yourself forced to admit that things aren't working out and do a forced landing before your old Navajo, Baron, C402 or C404 makes that decision for you. Don't be too optimistic, in other words!
3rd Nov 2011, 18:17
Having done more single engine performance test flights on light twins than I care to remember, a couple of pointers.
1. The Vmca (Blue line speed) is calculated at full power and sea level, at JHB density altitudes a normally aspirared engine gives about 75% power (approx). This means single engine Vmca is about 3-5 Kts below blue line.
2. 5 deg into the live engine and 1/4 ball out are must haves, if not they don't climb, the the exeption being a BN2A which just point blank refused to climb no matter what.:sad:
4th Nov 2011, 08:09
Good post Chuks, that pretty much sums it up. They are always crashing and there are always a whole bunch people saying how they shouldn’t have.
Piston twins have a poor safety record, and when you look at departure accidents with an engine inoperative the stats are truly concerning. It doesn’t seem to much matter if its hot, cold, high alt or sea level, very few manage to fly away on one engine. If you go through the NTSB reports you find aircraft in ideal conditions (cold, sea level, pilot only, etc) that never made it home from an emergency. I accept technique is critical but when you are talking about an aircraft where closing the cowl flaps makes the difference between life and death (and that’s true for a PA31) you have to admit that you are sailing very close to the wind.
Piston twin accidents also have a poor survivability rate. The speeds are usually higher (except in a BN2) and unlike in a piston single where you are sitting behind the densest part of the aircraft, in a twin you have little more than a nose cone between you and the rapidly approaching terrain. Also Avgas is rather volatile stuff and is mostly stored just behind the hot engine bits so post-crash fires are common and almost certainly survivable.
Piston twins in general are a cost effective solution. The acquisition price is usually low, they have considerably more utility than piston singles at a fraction of the running cost of a turbine powered alternative. You may save some money but what you lose is safety margin. Your piston twin may serve you well for years but if you are ever unlucky enough to have a dreaded engine failure on take-off you will need lady luck to smile on you. If she doesn’t your peers will be shaking their heads saying “it shouldn’t have happened”.
I’m sure soon we will hear all the “It can be done” stories and I accept that some great aviators amongst us have clawed their way home under horrendous conditions. However an average pilot in an average light twin with a departure engine failure will on average not be making a safe landing on his next return to earth.
The Ancient Geek
4th Nov 2011, 09:36
We all train for engine failure on takeoff.
The problem is that this is never done hot & high at MTOW.
Baron Von Mildred
4th Nov 2011, 21:37
The reason we don't train for engine failure after take off at MTOW hot & high in a piston twin is because it can't be done!!! You can only try to find a suitable crash site (maybe).
I survived an EFATO at 100ft in a piston twin. Not because I'm a shit hot pIlot, because God must have been looking after me! Light load, lowish temp, flat terrain, lowish elevation, and it flew -just!
I knew an engineer who was along for the ride in a Baron, in Tanzania, I think it was. He described how one of their donkeys died at altitude yet the pilot failed to feather the engine. The speed decayed, the aircraft descended and they finally landed on a railway with a terrible thump, breaking the engineer's leg. Well, he must have survived, since he told me the story, but...
Long ago, in the U.S.A., we could commit all sorts of comercial aviation with a Commercial licence. For airliners, you needed an ATP but otherwise a CPL did just fine. So some unfortunate holder of a CPL lost an engine on a Navajo while departing from 10 thousand feet of our finest concrete. He could, of course, have simply landed on what was left, or perhaps tried to feather the failed engine and gone for blue line to see what that should bring. Instead he got into a big argument with drag and gravity, and drag and gravity won, when he rolled his Navajo into a big ball and the FAA in its wisdom made everyone get an ATP. Sigh... So those two Colgan pilots who managed to stall and then go straight in in a nice, new Dash 8 through what seems like mind-boggling failures of basic airmanship... ATP holders both of them!
I don't know why it is, but hanging two engines on just about anything does seem to bring out the optimist in almost all of us. Should we bring back the tri-motor?
7th Nov 2011, 13:06
Warloc67, Surely you mean the RED line Vmca speed - Not Blue Line Vyse speed ;) Have flown Navajo Panther 350 HP in a PA31-310 Navajo Airframe.........What a nice machine to fly and immaculate all round !!!
Now based in Namibia.
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