Navajo Tips and Tricks

FlyByWire22

Well-Known Member
Afternoon all,

I just got a new job flying a PT 91 Navajo around Florida and to the Bahamas. Extremely excited for this opportunity and already have about 10 hours in the airplane. It is a Panther conversion - minus the optional winglets. Turbo engines, vortex generators, and q-tipped propellers. Just wondering if some of you veteran Navajo drivers could give me any tips that you've learned over the years flying this capable machine. Just looking at decent planning, fuel management, and in particular how to treat those twin turbo engines right.

Thanks!
 
The Navajo is my favorite I've ever flown, it's not the best airplane I've ever flown, but it holds a special place in my heart. Here are the tips I can come up with off the cuff.

The basic flow for all operations is a cross. Start on the left by the CB panel, cross left-to-right across the panel all the way across then go top to bottom.

Any time you touch the boost pumps, touch the fuel selectors - tie those together and you'll never takeoff or land on the outboards.

Do the same thing with the gear handle and the prop-sync. Any time you touch the gear, touch the other. Wait until the handle moves all the way back to the down-neutral, or up-neutral position before you take your hand away from the vicinity of the gear handle.

Short field takeoffs are a non event in the thing, and if its not too high or hot, you can very easily operate out of strips as 2400'. Anything less than about 2400' or anything with any significant contamination and you're going be busy, but under the right conditions you can depart much shorter - I personally watched my best friend depart an 1800' strip in a Navajo, but it was windy and the airplane was light.

Start the left engine first if you're around people a lot when you start. You can see it a lot better than the right in my opinion. Speaking of starting, whichever one you start first, after it's running do the gear pump test. When you go to shut down, shut down whichever engine you started first to test the other pump. Works great, and then you don't have to keep track of alternating starts, etc.

If you've got TSIO-540s, then you should plan on 40gph in cruise. That's a pretty reliable fuel estimate in my experience. If you're going higher than about 8,000 above where you took off from and you were going to be really short on fuel, you might break out the books, but for short flights (say less than 1 hr) and flights down low 40GPH is pretty accurate.

If you have GPS, start your descents so that you can do 500fpm on the descent off of the ETE time on the GPS. To do this, just double the amount of altitude you have to lose and start down at that many minutes. If you don't have a GPS 5-to-1 and 500fpm is fairly close, then you can fine tune when you get close. Regardless, unless absolutely necessary, fly at 500 fpm on the way down hill. On the way uphill, 120 to 140 KIAS is a pretty good climb speed.

As far as engine management, I know a lot of people will say that shock cooling doesn't exist...but, even Lycoming defines excessive power reductions (check out their operating manual for the engine - it's free online and it's important reading). At my old job, we limited our power reductions to no more than 2" MP per 1 minute of time initially and we NEVER, had any problems with anything. Other operators didn't have quite the same track record. I personally just planned out my descent so that I was able to reduce power at around 1"MP per minute until I was down around 23 to 25" MP (depending on temperature, at -40° I tend to be a little more conservative). If you do this right at 500fpm you'll have no problems with speed or staying ahead of the airplane.

I have a bunch of training aids and resources that I made for my old job that I can give you in a dropbox file if you want them. Again, it's my favorite airplane and I hope you enjoy flying it. Let me know if there's anything else I can get you!
 
Love, love the Navajo. It doesn't git r dun quite as well as an up engine caravan but it can be a lot more fun to fly. Get good flows down because it is a busy busy airplane. Which is one of the things I like about it.
The following is based on the late model chieftain, with good gear and calco flaps so some or none of it may apply to your bird. If it's a 60s -310, good luck, you're on your own but any of the later model -350s and -325s should be about the same.
Honestly, I don't bother with the hyd pump check other than first trip of the day and last trip of the day.
Takeoff-balls to the walls until 500' then 38" 2400 32 GPH (the POH will tell you that the ABSOLUTE MINIMUM fuel flow at 85% [38/2400] is 30, we've had good luck keeping it higher). If head temps will allow it, climb at the blue line. The sooner you get to cruise altitude, the sooner you can get the power and subsequently the fuel flow down.
I can't emphasize this enough-with the power up the airplane will absolutely devour fuel. It's a characteristic of big turbo recips that they need extra fuel at high power to keep things cool. You can run 75% power (33/2400) all day long but it's loud, burns ~10% more fuel per trip, and the time savings are negligible over the 65% we usually run. I've played around a little bit and if you're not in a big hurry you could even use Amflight power (~26/2200) and really get fuel flows and engine temps down with a nearly negligible change in block time. All that said 90% of my cruise time has been spent at 30"/2200/18 GPH per side. One point that I do agree with Pat on is to ballpark a block fuel burn of 40 GPH, at least until you get the time in that airplane and your engine management down to where you have the feel of your airplane and operation.
As far as cruise altitude, depending of course on winds and stage length, 5500/6500 are generally the most efficient.
For descent planning, here is what I do.
VFR: same as Pat, altitude times two is minutes out to start your 500 fpm descent. Plan 2" of MP reduction every 2 minutes (making a change smaller than 2" MP can be difficult, the turbos can be just a bit touchy) and plan to hit the airport at 24" MP. If you're following so far, that means I'm typically making my first power reduction to 28" at 6 minutes out, 26" at 4 minutes out, etc. this profile puts you in a good spot to level at pattern altitude and into flap then gear then more flap range (do you have the 162 knot flaps and 153 knot gear?). VFR pattern flaps 15 on they downwind, gear down abeam touchdown and run a gump check (gas [tanks and pumps] undercarriage mixtures set [dont usually touch them between setting cruise power and shutting down on the ramp, unless I have to do an extended level off for spacing or whatnot] props 2400) then flaps full turning final. A lot of guys like to eke the flaps in like 2* at a time, that is a good idea with the dukes flaps but stupid and unnecessary with the calcos. Look for about 100 down final and 90 crossing the threshold, I've always found she lands real nice with full flaps and idle power. Careful to let the nose down easy while you still have some speed and elevator authority, otherwise she'll slam down.
IFR descent profile is similar to VFR, except plan everything to the FAF instead of the airport, and put flaps 15 in established on the FAC. That should put you at 24" and min altitude at the FAF, at which point you should be able to drop the gear, then depending on when you break out flaps full when you have the runway in sight. Easy peasy.
Two things I can't emphasize enough: first, you have to think ahead when you're flying this thing or it will eat your lunch. The handling characteristics are amazingly docile for a cabin class twin, especially if you have the VGs, but it is just fast enough to bite you especially if you are coming from a 172 or similar. Second, your maintainers really, really need to know what they're doing. There are a million little gotchas that can really ruin your day on this machine, from the exhaust system (AD mandates an inspection every 60 hours) to the gear (one little oversight there led us to slide ours in on the nose, oops). Even the things that won't bite you hard can get gremlins that will either AOG you or just drive you and your mechanics crazy.
 
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A few other thoughts. Don't be afraid to run out the outboards in cruise, if your bird has the "FUEL BOOST INOP" lights on it they will illuminate a few seconds before the engine starts to surge (just enough time to switch tanks). Also learn the "Chieftain Circle" checking the rear cabin door, left nacelle locker, nose door (triple check!), right nacelle locker, then up over the wing and in (assuming you have the pilot door).
 
Best advice I can give is if you mess up and aren't stage cooled simply don't land yet, fess up and fly around a bit. Also when in doubt just slow up and put the gear down, it will pretty well save you when you might otherwise not have been able to descend.
 
I found that if you started the standard 2" per 1 minute stage cool down to 18" from 30" - 6 minutes, put the flaps out at the piper recommended flaps approach speed and then the gear at the piper recommended flaps full speed, coming downhill at 3 degrees, you'll hit everything right on the numbers. It's like they designed it that way(they did). Now start making up numbers out of nowhere and it can be a handful.
 
I found that if you started the standard 2" per 1 minute stage cool down to 18" from 30" - 6 minutes, put the flaps out at the piper recommended flaps approach speed and then the gear at the piper recommended flaps full speed, coming downhill at 3 degrees, you'll hit everything right on the numbers. It's like they designed it that way(they did). Now start making up numbers out of nowhere and it can be a handful.

Yeah, amflight wouldn't drop the gear until like 120 KIAS or something silly like that if memory serves...
 
A few other thoughts. Don't be afraid to run out the outboards in cruise, if your bird has the "FUEL BOOST INOP" lights on it they will illuminate a few seconds before the engine starts to surge (just enough time to switch tanks). Also learn the "Chieftain Circle" checking the rear cabin door, left nacelle locker, nose door (triple check!), right nacelle locker, then up over the wing and in (assuming you have the pilot door).
It does indeed have the inop lights, so I'll try this tomorrow, got a 3 hour flight to the out islands.
 
Best advice I can give is if you mess up and aren't stage cooled simply don't land yet, fess up and fly around a bit. Also when in doubt just slow up and put the gear down, it will pretty well save you when you might otherwise not have been able to descend.
Used the gear drag today, love that technique. Perfect for keeping the power stable, but slowing her up nicely
 
It does indeed have the inop lights, so I'll try this tomorrow, got a 3 hour flight to the out islands.

Personally, my technique was to just burn down to a quarter tank then switch to the inboards so I didn't terrify the passengers if I got distracted at the wrong time. Do you have the extended tanks or the normal range tanks? You can't really carry a whole lot if you're topped out on fuel. 182 gal usable isn't really a whole lot.
 
Personally, my technique was to just burn down to a quarter tank then switch to the inboards so I didn't terrify the passengers if I got distracted at the wrong time. Do you have the extended tanks or the normal range tanks? You can't really carry a whole lot if you're topped out on fuel. 182 gal usable isn't really a whole lot.
Just get her on autopilot and sit there watching the fuel pressure gauge. If things get busy, switch before you forget.
 
Just get her on autopilot and sit there watching the fuel pressure gauge. If things get busy, switch before you forget.
The red fuel lights mean you have about 5 seconds and a twitching fuel pressure gauge was a few seconds more iirc.
 
Yeah, amflight wouldn't drop the gear until like 120 KIAS or something silly like that if memory serves...

It was 125 knots. They did that because some of the birds had 125 knot landing gear extension speeds and the rest had the 150 (IIRC). So 125 knots covered the whole fleet, and reduced the chances of someone overspeeding the gear on the slow gear birds.
 
Personally, my technique was to just burn down to a quarter tank then switch to the inboards so I didn't terrify the passengers if I got distracted at the wrong time. Do you have the extended tanks or the normal range tanks? You can't really carry a whole lot if you're topped out on fuel. 182 gal usable isn't really a whole lot.
Yeah, our bird only has 182 usable
 
It was 125 knots. They did that because some of the birds had 125 knot landing gear extension speeds and the rest had the 150 (IIRC). So 125 knots covered the whole fleet, and reduced the chances of someone overspeeding the gear on the slow gear birds.
Late model chieftain is 153.
 
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