Cherokee 140 pushing the limits

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RonP

Pre-takeoff checklist
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I am planning a flight that will max out my airplane. I am looking for opinions as I have never flown it at max TOW and less than half tanks of fuel. It is a 1969 Cherokee 140B stock except for the following:

  • climb prop instead of the stock prop
  • LED landing light
  • uAvionics SKYBeacon

I had a W&B done 5 years ago. I am planning a 36 minute flight from south ‘Jersey from 17N (162’ MSL) to KWWD (Cape May 22’ MSL) with 4 adults. Per the W&B I will be at max TOW (2,150lbs) with 20 gallons of fuel of which 18 is useable. Per the performance charts with a density altitude on a hot day of 2,000 feet I need 2,150’ to clear a 50 foot obstacle (maybe less climbing at Vx 75mph) to clear trees at the end of the 3,500 foot runway. I should be able to make it to Cape May and back with the 20 gallon fuel on board or even top off to 20 gallons before leaving Cape May. I know the climb will be anemic but the numbers show this is within performance limits. I have heard tales of the 140 not being a 4 adult airplane with disastrous results. The adults are not big people with me at 175lbs, right seat person at 152lbs and 2 small women in the back seat at 120lbs and 156lbs. Am I looking to be another aviation related statistic or safe to make the trip?
 
If you're in the envelope and not over max gross, I don't see a problem. The "statistics" do what you're talking about, but with a couple 250 pounders up front (I'm not judging I'm that size too) and full tanks.

Now I must ask, what did the women in the back seat do to deserve the penance of riding in the back seat of a 140? Are they your friends? They won't be for long :D
 
It will probably use more runway than the POH says, climb slower than the POH says, etc. That POH was meant for when the plane was new, which it ain't no more! Would I make the flight? You betcha! Should you? Only you could answer that.
 
The women in the back seat are fortunately less that 5’. One is my wife which many would say is punishment enough. The other is the girlfriend of the right seat co-pilot who is a college student that is interning with me for the summer. I took them both for a short flight Saturday which was a new experience for them both. The downside was he hasn’t stopped yammering about the flight all week. Cape May has a very nice museum with a WWII theme since it was an active base during the WWII. My wife and I enjoy going to the museum and thought it would make a great trip for all of us. Since I just filled up the Cherokee I have awhile to burn some fuel before I attempt this flight. It may just be spooky being used to climbing at over 1,000 FPM and with that load barely waking out 600FPM. Thanks for the replies.
 
Your good…just watch your numbers and enjoy!
 
I fly our Cherokee 140 (granted, it's the 160 HP STC'd engine) at gross weight all the time. Me and my wife up front, the dog and two travel bags in the back, plus full fuel usually puts us right at MTOW. Never had an issue getting off the ground or climbing and where I live, DA of 2,000+ is a pretty normal or even good day. Don't expect a rocket like climb - it's more of a shallow, relaxed 400 fpm climb until you hit a nice updraft but if you're within the limits, you're good to go if your engine is in good health and you get max power out of it.
 
MauleSkinner said:
Do you have any idea how your technique in your airplane compares to the performance charts?
Click to expand...

First I must compliment all those that have replied with good advice. I have never compared the performance or my technique to the performance charts. Since I have a lot of fuel to burn to do this flight I will be comparing performance and pilotage back to the performance charts to see how real world compares to paper.
 
RonP said:
First I must compliment all those that have replied with good advice. I have never compared the performance or my technique to the performance charts. Since I have a lot of fuel to burn to do this flight I will be comparing performance and pilotage back to the performance charts to see how real world compares to paper.
Click to expand...
Runway lights are generally 200’ apart. :)
 
RonP said:
with 20 gallons of fuel of which 18 is useable
Click to expand...
How will you know you have exactly 20 gallons of fuel? When I see people do these 'down to the wire I-can-go-if-I-have-36.3-gallons' calculations I always wonder how they measure fuel that exactly? Unless you have a well calibrated dip stick (which you might) or really really really trust your totalizer I just can't see how you can get any closer than "yeah it's around tabs" in the majority of our planes..

As far as the flight, if you're within the POH limits then you're okay. However, the plane does fly differently when loaded.. and the performance today in 2022 is likely at least somewhat less than what it was when the plane was new. The POH figures are ideal best case scenario numbers developed by engineers and test pilots. I doubt the planes I fly behave like new nor are my skills nearly as good as a paid test pilot

My biggest concern would be actually being within WB. You know people weigh more than what they advertise. They get on a scale nude, or nearly nude, that's their weight.. usually rounded down slightly. Now you have to factor in odds and ends like water bottles, headsets, wallet, phones, misc bags, and the "I lied about my weight" factor. I always pad people's weights by a good 10-15 lbs
 
Good advice about padding people's weight. I even do that with myself lol. I keep hearing people on the forum saying things along the lines of "planes don't perform as they did back in the 60s when they were new" or something to that effect. Why is that the case? I mean, my 1966 airframe should be as efficient as it was back in 1966 - maybe even more efficient after adding some speed mods. Now, I agree, a 2,000 hour engine might not perform as well as a new engine but if you have an old airframe with a newer engine (mine is only about 300 hours and a few years old), shouldn't I get pretty close to book values or does something on the airframe make the plane slower or less efficient than when it rolled out of the factory in 1966?
 
Chrisgoesflying said:
Good advice about padding people's weight. I even do that with myself lol. I keep hearing people on the forum saying things along the lines of "planes don't perform as they did back in the 60s when they were new" or something to that effect. Why is that the case? I mean, my 1966 airframe should be as efficient as it was back in 1966 - maybe even more efficient after adding some speed mods. Now, I agree, a 2,000 hour engine might not perform as well as a new engine but if you have an old airframe with a newer engine (mine is only about 300 hours and a few years old), shouldn't I get pretty close to book values or does something on the airframe make the plane slower or less efficient than when it rolled out of the factory in 1966?
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If your engine is in good health with good compressions you're probably close. But you never know with rigging changes, peeling paint, etc., everything adds up. I fly club beater rentals so I just assume the planes are only about half as good as they were new haha
 
RonP said:
It may just be spooky being used to climbing at over 1,000 FPM and with that load barely waking out 600FPM. Thanks for the replies.
Click to expand...

You have much better climb characteristics than I do in my Cherokee but you said you had a climb prop and you’re a lot closer to sea level than I am. I’m lucky to hit 1,000 fpm on a winter day with just me. In the summer I’m lucky to hit 500 fpm.
 
I’ve flown 4 in a Warrior to FL, MO, & a few other places, yes, 2 were midlin kids.

You have to mind density altitude. A ‘fuel-straw’ is very helpful. After that, chose your airports more carefully. The edge isn’t sharp, it’s gray. A long runway, +5 psi extra in the tires, a few extra knots, gentle rotation, keeping a few extra knots. I like a known fuel quantity in one side for landing, don’t mind emptying(or almost) the one side in cruise.

Again, the margins in March are likely much better than a 95 degree Summer day, pilots are supposed to be thinking.
 
How much fuel do you expect to use in 36 minutes plus climb /traffic/etc? Some days I take off without a wait but sometimes there’s some IFR dude and 3 trainers blocking things for a while (usually when it’s 95 and sunny)
 
RonP said:
I am planning a flight that will max out my airplane. I am looking for opinions as I have never flown it at max TOW and less than half tanks of fuel. It is a 1969 Cherokee 140B stock except for the following:

  • climb prop instead of the stock prop
  • LED landing light
  • uAvionics SKYBeacon

I had a W&B done 5 years ago. I am planning a 36 minute flight from south ‘Jersey from 17N (162’ MSL) to KWWD (Cape May 22’ MSL) with 4 adults. Per the W&B I will be at max TOW (2,150lbs) with 20 gallons of fuel of which 18 is useable. Per the performance charts with a density altitude on a hot day of 2,000 feet I need 2,150’ to clear a 50 foot obstacle (maybe less climbing at Vx 75mph) to clear trees at the end of the 3,500 foot runway. I should be able to make it to Cape May and back with the 20 gallon fuel on board or even top off to 20 gallons before leaving Cape May. I know the climb will be anemic but the numbers show this is within performance limits. I have heard tales of the 140 not being a 4 adult airplane with disastrous results. The adults are not big people with me at 175lbs, right seat person at 152lbs and 2 small women in the back seat at 120lbs and 156lbs. Am I looking to be another aviation related statistic or safe to make the trip?
Click to expand...
You may want to go over your ‘abort’ scenarios. If the engines performance isn’t as expected, or you’ve miscalculated weight, you’ll have some clues before you get airborne. Have a ‘if I’m not in the air by point,’ I’m aborting. Maybe not in the air by. There are some formulas based on percentage of airspeed by a certain point. Like if you haven’t reached x% of Vr by y distance, abort.
 
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Pick your passengers up at KMIV. Do a short field take off and make a mental note of your take off and 50’ spots and if you don’t think that will work at your destination just return to KMIV.
 
Be sure to check for the Rehoboth TFR. It's going up again from 6/17-6/20. KMIV is good, but KWWD is in the outer ring.
 
I have a calibrated fuel stick for measuring fuel. I have never checked it for accuracy and have to rely on the manufacturer that it is more accurate than guessing how much fuel there is in the tanks. 20 gallons of gas of which 18 is useable is a concern even though the flight is 36 minutes enroute. I will recalculate everything including fuel burn and point of aborting many times before the actual flight including headwind on the day of the flight. As my shop teacher used to say, “think THREE times, measure TWICE and cut ONCE”.
 
As Beech put on the sheet metal drawings for the Staggerwing…
“Cut to size, trim to fit, kick in place.”
 
This thread keeps ringing, or maybe gonging, in my mind. Thinking about planning down to the minute and cutting onboard fuel to a thin margin is troubling to me. Here’s why it rings in my head:

About three years or so ago, I agreed to fly to the Houston area to pick up my son in law because he was leaving his Baron B58 for some major avionics and interior retrofit. About two days before we made the trip, it was in the news that a B58 had gone down at Kerrville, Tx killing all aboard. The Baron was owned and flown by a Houston area ATP rated pilot who just enjoyed flying and was always quick to offer rides because he enjoyed flying.

My SIL was a little upset over hearing of the accident involving people he didn’t know, maybe because it was in a plane very much the same as his. I could tell by the way he talked about it that the accident had gotten his attention and he was wanting to learn more about the circumstances.

When my SIL and I made the trip, he got away a little earlier than me and could of course outrun my Mooney, I got there, taxied in and found my SIL in the shop owners office in the midst of a somber conversation. It turned out that the shop owner, the downed pilot and the local Beech representative were all very close friends. The shop owner said that the pilot had loaded the plane to the max and fueled enough for the trip. They ended up in IMC and an unexpected wind change that caused them to have to pass the airport to shoot the approach from the opposite direction rather than going straight in. They ran out of fuel on the approach, during the reversal leading to the approach as I recall, and for whatever reason, the plane went down flat. All passengers remained in their seats after slamming into the ground. There was no fire. Tanks were bone dry.

The shop owner said that his friend the Beech Rep had been very upset and was saying something to the effect that the plane would have flown heavy, but he should have carried enough fuel. You have to have fuel!

Obviously the best decision would have been to reduce weight AND carry adequate fuel margin, but you MUST HAVE FUEL!

Even on a beautiful VMC day with no clouds in the forecast for the next week, that flight can hold unexpected events. Don’t scrimp on fuel! Have enough fuel and plenty of reserve for the trip even if you have to leave baggage on the tarmac.

Flying is SERIOUS life and death, unforgiving business. Take it seriously.

My $0.02,
 
I fully agree with all the messages of "have enough fuel on board" but nothing in the OP's post suggests that he is looking to skimp on fuel. He said he'll have 18 gallons usable on a calculated 38 minute flight. His Cherokee should burn (if leaned correctly) about 8 gph - for safety I always calculate with 10 gph just to be safe. Hence he will burn right around 6 gallons on the trip, leaving him with 12 gallons reserve. Would I go there and back on 18 gallons? No, I would, as OP suggested, top of to 18 gallons at the destination airport. 12 gallons reserve in a Cherokee, that's over one hour of reserve fuel. More than enough for day VFR. You only need 30 minutes reserve to be legal. I feel better with an hour reserve on board but OP should have more than an hour, if his trip calculations of 38 minutes is correct.
 
MBDiagMan said:
This thread keeps ringing, or maybe gonging, in my mind. Thinking about planning down to the minute and cutting onboard fuel to a thin margin is troubling to me. Here’s why it rings in my head:

About three years or so ago, I agreed to fly to the Houston area to pick up my son in law because he was leaving his Baron B58 for some major avionics and interior retrofit. About two days before we made the trip, it was in the news that a B58 had gone down at Kerrville, Tx killing all aboard. The Baron was owned and flown by a Houston area ATP rated pilot who just enjoyed flying and was always quick to offer rides because he enjoyed flying.

My SIL was a little upset over hearing of the accident involving people he didn’t know, maybe because it was in a plane very much the same as his. I could tell by the way he talked about it that the accident had gotten his attention and he was wanting to learn more about the circumstances.

When my SIL and I made the trip, he got away a little earlier than me and could of course outrun my Mooney, I got there, taxied in and found my SIL in the shop owners office in the midst of a somber conversation. It turned out that the shop owner, the downed pilot and the local Beech representative were all very close friends. The shop owner said that the pilot had loaded the plane to the max and fueled enough for the trip. They ended up in IMC and an unexpected wind change that caused them to have to pass the airport to shoot the approach from the opposite direction rather than going straight in. They ran out of fuel on the approach, during the reversal leading to the approach as I recall, and for whatever reason, the plane went down flat. All passengers remained in their seats after slamming into the ground. There was no fire. Tanks were bone dry.

The shop owner said that his friend the Beech Rep had been very upset and was saying something to the effect that the plane would have flown heavy, but he should have carried enough fuel. You have to have fuel!

Obviously the best decision would have been to reduce weight AND carry adequate fuel margin, but you MUST HAVE FUEL!

Even on a beautiful VMC day with no clouds in the forecast for the next week, that flight can hold unexpected events. Don’t scrimp on fuel! Have enough fuel and plenty of reserve for the trip even if you have to leave baggage on the tarmac.

Flying is SERIOUS life and death, unforgiving business. Take it seriously.

My $0.02,
Click to expand...

I have also considered the possibility of getting to the destination and for some reason the runways are closed. There are 3 airports along the route and for a 36 minute flight that puts them 12 minutes apart if I have to divert. I do appreciate the concern and the unfortunate story due to fuel starvation. When I do a long cross country I never fly below 1/2 the fuel capacity. This strategy paid off when flying from ‘Jersey to Nashville and due to weather being stuck above the clouds going over the Allegheny mountains at 8,500 feet and had to go 100 miles north to find an opening big enough to descend thru. I also plotted my path over or close to airports along the way just in case of a problem.

As Chrisgoesflying stated when arriving at the destination there should be a large margin of fuel left. I “may” even be able to fly back without refueling however it is safer to replenish the fuel burned getting there for the flight back even if it is only 5 gallons.

I hear flying nude is only enjoyable in open cockpit airplanes so that’s off the table. Plus my wife has more authority over my flying privileges than the FAA!
 
It seems like your reserve might be a bit tight if you don't fuel up for the return trip. I mean what if someone does a gear up landing when you're on downwind and the airport closes?
 
I checked fuel burn with my O320 years ago, modest, medium cruise power settings. I came up with 7.25 GPH. For simple math I used 8 for planning. The other key is to have that known quantity in the selected tank for landing. Back in the day I would run a tank to fumes in cruise. I don’t want to say ‘dry’ cuz the most I ever got to was a slight engine stumble, low pressure was 1st. Yes, fuel is the true low-hanging fruit of accident prevention.

One plans for shorter legs, part of the fun anyway.

You could have 10 tricks up your sleeve, and it still won’t be enough heavily loaded, 2000’ grass runway. One has to always evaluate the planned course of action, adjust as needed.
 
sourdough44 said:
I’ve flown 4 in a Warrior to FL, MO, & a few other places, yes, 2 were midlin kids.

You have to mind density altitude. A ‘fuel-straw’ is very helpful. After that, chose your airports more carefully. The edge isn’t sharp, it’s gray. A long runway, +5 psi extra in the tires, a few extra knots, gentle rotation, keeping a few extra knots. I like a known fuel quantity in one side for landing, don’t mind emptying(or almost) the one side in cruise.

Again, the margins in March are likely much better than a 95 degree Summer day, pilots are supposed to be thinking.
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Ron, your original post is very good and you've done a lot of homework. I would say that most pilots that get into trouble do so because they haven't done their due diligence up front. In this case I agree that you should be mindful of density altitude changes and how that affects your airplane's performance on this flight. What I would do is make a quick chart with air pressure and air temperature at 85, 90, and 95 degrees and see how your takeoff and climb performance at each airport changes. You might be surprised at what you find. If your safety margins can be maintained at all three temperatures then you are good to go. You may find that your safety margins diminish too much at 95 but are OK at 90. I would consider that to be critical information for the safety of your flight.

Have FUN! Fly safe!
 
Two comments:
  1. Don't assume you will get book performance. Leave plenty of margin from book to account for a less than spanking-new engine, inexperienced technique at this loading, and a slightly overweight aircraft compared to the logs. Heat and humidity will eat into that margin quickly. You might want to get some experience handling your aircraft at higher loadings, or at MTOW at an airport with a long runway. The aircraft will feel very different with a more rearward CG and heavier loading.
  2. Don't skimp on fuel, within your loading limitations. Even for a short flight, I'd still want 45-60 minutes reserve if possible. A short flight is going to have a higher proportion of high-fuel-consumption operation for takeoff, climb, and possibly full-rich operation during final approach. This will significantly increase your typical "block" fuel consumption. In my current aircraft (O-320 engine) a one hour flight has about 0.5 gph higher block fuel consumption at typical cruise settings than for a 3 hour leg.
In my younger days, I operated an AA-A1 at MTOW frequently, which was nearly required with a passenger on board. It was short-legged to start with, holding only 22 gal. I never skimped on reserve fuel, and the shortest runway I flew out of was 2600 feet, which was uncomfortably close margins with trees at the end of the runway. The book says about 1600-2000 feet to clear a 50 foot obstacle depending on the temperature. No way I'd fly out of 2000 feet over a 50 foot obstacle with that plane at MTOW. You can PROBABLY do it most of the time unless something unusual transpires, then you are SOL. I eventually set my personal minimum at 3000 feet. The extra margin comes in handy if there are gusty conditions, shifting winds, or mild wind shear. I have encountered such conditions once when heavily loaded, and that margin avoided an incident.

It sounds like you are doing your homework. Be safe, and plan for ample safety margins.
 
This talk about planning it on the edge.....
I'm reminded of a couple flights I did when the ink was still wet on my certificate.

actually I think one might have been a student solo...anyway....
I did a cross county, got distracted, and forgot to lean for quite a while, burned a lot more gas than planned.
and now that I'm thinking... one time left 10 degrees of flaps in for a while after takeoff once as a student.
I know...student pilot kind of mistakes, not things most would do with experience....
Anyway...the point is...you get distracted, make boneheaded mistake. (I know you don't do it, but I promise everybody else does at some point)

Sometime not too long later, with a fresh PPL, I made a flight to my home town in a 172. Would have been 2.5-ish hours. Landed and was met at the airport by my sister and brother in law. Took them on a a quick sight seeing lap around town. I should have had more than enough fuel...and although I don't recall I'm sure i would have looked into the tanks with a quick preflight but it wouldn't have been a measured thing.. After we got going and away from the airport a few miles with guests onboard I had this horrible thought...still shakes me thinking about it now.... did I lean properly on the flight into town? Do I really have enough gas on board?
 
Brad W said:
This talk about planning it on the edge.....
I'm reminded of a couple flights I did when the ink was still wet on my certificate.

actually I think one might have been a student solo...anyway....
I did a cross county, got distracted, and forgot to lean for quite a while, burned a lot more gas than planned.
and now that I'm thinking... one time left 10 degrees of flaps in for a while after takeoff once as a student.
I know...student pilot kind of mistakes, not things most would do with experience....
Anyway...the point is...you get distracted, make boneheaded mistake. (I know you don't do it, but I promise everybody else does at some point)

Sometime not too long later, with a fresh PPL, I made a flight to my home town in a 172. Would have been 2.5-ish hours. Landed and was met at the airport by my sister and brother in law. Took them on a a quick sight seeing lap around town. I should have had more than enough fuel...and although I don't recall I'm sure i would have looked into the tanks with a quick preflight but it wouldn't have been a measured thing.. After we got going and away from the airport a few miles with guests onboard I had this horrible thought...still shakes me thinking about it now.... did I lean properly on the flight into town? Do I really have enough gas on board?
Click to expand...

Brad w,

Of course I never make boneheaded mistakes “that I admit to”! However to my credit none of the mistakes never resulted in night sweats and they never began with “hold my beer” either. One thing I found useful which might be a result of the engineer in me is making a second checklist for flights that are outside of my usual destinations. The second checklist makes sure I don’t forget to do something like switching tanks periodically, verifying land marks, frequencies to monitor, etc. Even for this 36 minute flight I will have a second checklist for items that are important for the safety of the flight. This does not eliminate any boneheaded issues but will greatly reduce them from occurring.

I also find going over the pre-takeoff check list again after takeoff has helped me catch things I may have missed. Not that it helps during takeoff but a reminder I got casual with the checklist and filed away in lessons learned.
 
I'm going to do one of my "this will sound like I'm being a jerk but it's not intentional" posts.

1. I wouldn't want to be in the back seat of an airplane when the guy in front, single pilot, is his first time flying anything max gross.
2. I don't trust 70s era performance charts at all. I know of 3 Cherokees that I'd fly that route with, full gross but without rear seat passengers, at 85F without hesitation. But I don't know your aircraft well enough to do that.

So I would recommend checking your short field technique with an instructor who does it all the time, and find out your numbers for your aircraft. If you're within day trip range of me, feel free to send me a PM for a recommendation. (I've got no stake in it.)
 
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