My last flight

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danman999

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danman999
I had an experience that has been bothering me. I hope this community might be able to provide me a little feedback on the incident and my actions as PIC.
I have about 220 hours in the C172S, and fly out of John Wayne KSNA in busy SoCal. Last week a friend and I intended to fly from KSNA to Montgomery Field KMYF in San Diego. 65 miles down the coast. Flown it dozens of times.
Run-up was normal, except for a left mag that dropped just a little more than 50 rpm of the right mag. It was so minor I attributed the excess drop to tach needle fluctuations.
Take-off roll was not normal. Usually the speed will creep up to about 40 KIAS, then rapidly accelerate to rotation 55 knots. It crept all the way up to 55 KIAS, no rapid acceleration. By this time I was very close to a point of committing on the runway, airspeed was alive, so I rotated.
I was only able to climb 200-300 fpm at 70 KIAS, when normally I can easily climb 600 fpm at 79 KIAS. Straight and level I could only achieve 80 KIAS.
While a normal full throttle on the aircraft yields about 2500 RPM, I was only getting 2200-2300 RPM maximum.
Throttle was full. Mixture rich. Both mags on. Oil temp and pressure in green. Positive fuel flow indicated. Both fuel tanks selected.
At 7 miles southwest of KSNA, on the coastline, we were at 2,500 MSL and struggling to climb any further. I went through the checklist about a dozen times to make sure it was not something I was or was not doing. However I could find nothing that I was doing wrong. Looking back the only thing I could think of is trying the electrical fuel pump. However I don’t think that would have made any difference. Fuel flow was positive. I don’t think I had fouled plugs, either. That would have cleared up on climb-out.
I called SoCal on the radio and requested a turn-back to the airport. I got a little rushed on my first approach, turned base too early and was too high and fast. I managed a go-around and landed without incident.
In hindsight I am wondering if that run-up discrepancy on the left mag should have told me something was wrong, or the sluggish take-off roll. Chances are I could have safely aborted, but I continued.
I filled out a maintenance squawk when I returned the aircraft (rental). I have not called them to ask what the A&P found, because I fear them telling me they found absolutely nothing.
Thoughts?
 
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danman999 said:
I filled out a maintenance squawk when I returned the aircraft (rental). I have not called them to ask what the A&P found, because I fear them telling me they found absolutely nothing.
Thoughts?
Click to expand...

They'll find something. Call them.
 
I’m not sure I would have made a huge fuss about the mag especially if it was smooth at the time but the slow take off roll would have had me spooked into an abort as I’m sure you didn’t have full rpm on the throttle for the roll.

good job keeping your cool and getting it back on the ground in some hectic airspace.

Carb heat pulled and left on could do that but you Said fuel pump so no carb.
Please keep us posted on what if anything they find. Has to be something.
 
danman999 said:
I had an experience that has been bothering me. I hope this community might be able to provide me a little feedback on the incident and my actions as PIC.
I have about 220 hours in the C172, and fly out of John Wayne KSNA in busy SoCal. Last week a friend and I intended to fly from KSNA to Montgomery Field KMYF in San Diego. 65 miles down the coast. Flown it dozens of times.
Run-up was normal, except for a left mag that dropped just a little more than 50 rpm of the right mag. It was so minor I attributed the excess drop to tach needle fluctuations.
Take-off roll was not normal. Usually the speed will creep up to about 40 KIAS, then rapidly accelerate to rotation 55 knots. It crept all the way up to 55 KIAS, no rapid acceleration. By this time I was very close to a point of committing on the runway, airspeed was alive, so I rotated.
I was only able to climb 200-300 fpm at 70 KIAS, when normally I can easily climb 600 fpm at 79 KIAS. Straight and level I could only achieve 80 KIAS.
While a normal full throttle on the aircraft yields about 2500 RPM, I was only getting 2200-2300 RPM maximum.
Throttle was full. Mixture rich. Both mags on. Oil temp and pressure in green. Positive fuel flow indicated. Both fuel tanks selected.
At 7 miles southwest of KSNA, on the coastline, we were at 2,500 MSL and struggling to climb any further. I went through the checklist about a dozen times to make sure it was not something I was or was not doing. However I could find nothing that I was doing wrong. Looking back the only thing I could think of is trying the electrical fuel pump. However I don’t think that would have made any difference. Fuel flow was positive. I don’t think I had fouled plugs, either. That would have cleared up on climb-out.
I called SoCal on the radio and requested a turn-back to the airport. I got a little rushed on my first approach, turned base too early and was too high and fast. I managed a go-around and landed without incident.
In hindsight I am wondering if that run-up discrepancy on the left mag should have told me something was wrong, or the sluggish take-off roll. Chances are I could have safely aborted, but I continued.
I filled out a maintenance squawk when I returned the aircraft (rental). I have not called them to ask what the A&P found, because I fear them telling me they found absolutely nothing.
Thoughts?
Click to expand...

The mag drop during runup does not sound all that unusual. However, one of the critical things to note during a takeoff roll is the rpm. It sounds like you didn't notice the low rpm until climb out. I am glad it all worked out, but you may want to add this to your pre-takeoff checklist.
 
You should have a pretty good idea what static rpm to expect, at the start of your takeoff roll. That alone could clue you in on a problem.

If it doesn’t feel right, pull power and abort. Troubleshoot on the ground.

Please let us know what you find out...
 
sarangan said:
The mag drop during runup does not sound all that unusual. However, one of the critical things to note during a takeoff roll is the rpm. It sounds like you didn't notice the low rpm until climb out. I am glad it all worked out, but you may want to add this to your pre-takeoff checklist.
Click to expand...

You are correct, I did not notice the low RPM until climb-out. By then obviously I was committed. Good point to always check RPM on takeoff roll. It was only about 300 RPM below where it should have been but boy that 300 RPM made a difference. That or there was something else going on.
 
SCCutler said:
You should have a pretty good idea what static rpm to expect, at the start of your takeoff roll. That alone could clue you in on a problem.

If it doesn’t feel right, pull power and abort. Troubleshoot on the ground.

Please let us know what you find out...
Click to expand...

Yes, I definitely learned some things that will always stick with me when I fly.
 
You did nothing most of us wouldn’t have done regarding the run up. But what I’ve found in my short time of flying is that when something is different when you’ve done it a hundred times before, even slightly, then there’s probably something wrong. That voice in my head needs to be listened to. But alas sometimes he’s brushed off. Don’t do that again.

Good job trying to check the checklist. I probably would have just stayed in the pattern and landed, not left the Airport environment. Did that once myself.

Funny how a little stress makes a go around necessary? Done that too. Imagine an engine out, with only one shot.

-Monday AM QB
-Rear seat pilot
 
Missing the low rpm on takeoff was one thing, now you know better, but continuing 7 miles on course instead of immediately returning to the airport could have been a much bigger mistake...

Bill Jennings said:
https://www.boldmethod.com/learn-to...0-rule-of-thumb-for-your-takeoff-this-summer/
Click to expand...

"So what is the 50/70 rule? It's a general rule for GA aircraft that says if you haven't reached 70% of your takeoff speed by the time you've reached 50% of the length of the runway, you should abort your takeoff."

Hah! If I'm not off the ground and climbing at 50%, something is very wrong...
 
Fouled plugs do not always clear up by themselves. Don’t take off with an abnormal mag drop or if you feel the engine running rough.

if you fly from a short field, 200rpm loss of power on takeoff might be a disaster.
 
danman999 said:
I had an experience that has been bothering me. I hope this community might be able to provide me a little feedback on the incident and my actions as PIC.
I have about 220 hours in the C172S, and fly out of John Wayne KSNA in busy SoCal. Last week a friend and I intended to fly from KSNA to Montgomery Field KMYF in San Diego. 65 miles down the coast. Flown it dozens of times.
Run-up was normal, except for a left mag that dropped just a little more than 50 rpm of the right mag. It was so minor I attributed the excess drop to tach needle fluctuations.
Take-off roll was not normal. Usually the speed will creep up to about 40 KIAS, then rapidly accelerate to rotation 55 knots. It crept all the way up to 55 KIAS, no rapid acceleration. By this time I was very close to a point of committing on the runway, airspeed was alive, so I rotated.
I was only able to climb 200-300 fpm at 70 KIAS, when normally I can easily climb 600 fpm at 79 KIAS. Straight and level I could only achieve 80 KIAS.
While a normal full throttle on the aircraft yields about 2500 RPM, I was only getting 2200-2300 RPM maximum.
Throttle was full. Mixture rich. Both mags on. Oil temp and pressure in green. Positive fuel flow indicated. Both fuel tanks selected.
At 7 miles southwest of KSNA, on the coastline, we were at 2,500 MSL and struggling to climb any further. I went through the checklist about a dozen times to make sure it was not something I was or was not doing. However I could find nothing that I was doing wrong. Looking back the only thing I could think of is trying the electrical fuel pump. However I don’t think that would have made any difference. Fuel flow was positive. I don’t think I had fouled plugs, either. That would have cleared up on climb-out.
I called SoCal on the radio and requested a turn-back to the airport. I got a little rushed on my first approach, turned base too early and was too high and fast. I managed a go-around and landed without incident.
In hindsight I am wondering if that run-up discrepancy on the left mag should have told me something was wrong, or the sluggish take-off roll. Chances are I could have safely aborted, but I continued.
I filled out a maintenance squawk when I returned the aircraft (rental). I have not called them to ask what the A&P found, because I fear them telling me they found absolutely nothing.
Thoughts?
Click to expand...

First, I am not busting your buns, but here are some things you could have done better. Accidents happen after a chain of events. It’s up to you to break the chain. I highlighted some parts of your story for discussion.


Event 1. Run up was was not normal. Pay attention to the little things in airplanes. That is the only warning we get sometimes and you can’t ignore them. The mag check values are there for a reason.

Event 2. Did you do a takeoff briefing on what you were going to do if the engine quit or was not producing full power? You didn’t seem to have a plan or to fully take control of this event.

Event 3. Take off roll not Normal and then you say you were committed. Never take a sick airplane into the air. Always check you full power RPM and oil pressure early in the takeoff roll. You have to pull the throttle when takeoff RPM or performance is below normal. The shortest runway at KSNA is 2887 ft at basically sea level. Takeoff roll in a 172 is -1000 ft. The landing roll distance is <1000 ft. What happened to the other 1/3 of the available runway? Even if you roll off the end of the runway at low speed it’s better than losing an engine after takeoff.

Event 4. Climb rate significantly below normal and you continued flight 7 miles SW of departure. You should have never left the airport and landed ASAP.

Event 5. You never confessed to ATC and never really admitted to yourself you had an emergency. You requested return to airport. You should have advised ATC you had an emergency (or at least an engine problem for immediate return) and did what you needed to do to save your souls. The tower would have activated their rescue crew and they are at least on their way had you crashed.

Event 6. You failed to properly plan the approach and had to go around. You never want that to happen because you may only have one shot at this. When you declare an emergency the tower would have given you any runway and any pattern you want to land.

Hopefully this event gives you pause to evaluate your ADM process and make some changes.
 
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I agree with @Clip4, the key to avoiding an accident is breaking the chain before its too late. The trouble is you never know when too late is.

(Forgive the Monday morning quarterbacking, but) I think the mistake you made was overlooking the cumulative aspect of the problems. Mag-drop of 55 rpm instead of 50, if there is no other issue I would probably still fly. It takes a little longer than normal to reach rotation speed if nothing else is wrong (not the case when you start with an abnormal mag drop), I would still rotate, it may just be an uneven throttle application. Long ground roll after a runup issue what aborts are for, pull the power, get on the brakes, it's better to meet the tree at the end of the runway after 400' of braking than during an attempt to climb.

Slow Climbs are always a reason to turn back. If I'm climbing at half my expected rate, I will not let the airport out of my sight until I know why (and fix it). Staying away from the ground is what keeps you alive if your plane's ability to do that is questionable, then park it.

Last (and this, in my opinion, is a problem in more experienced pilots too), Declare an Emergency! Reading NTSB reports, watching ASI video, it is horrifying how long it takes pilots to admit that there is a problem. Any time you are in the air, in a situation that is worse than you thought it would be when you were on the ground, it is an Emergency. It is easier to explain why you declared 100 "questionable" emergencies than it is for the NTSB to explain why you didn't declare one on your last flight. My friends give me crap for referring to my time landing a 150 without an electrical system as an emergency because it was basically just a no-flap landing. I have no hesitation about calling it an emergency landing because I don't want to get in the habit of trying to hide problems until they kill me (it was not a declared emergency, even though I dialed 7600 into the transponder ATC never saw it).

From the experience, I have in a few 172 airframes (though I will admit I have not flown a 172s), even the 150hp should get over 300fpm in December if it is at or below gross. There is something wrong with that plane, if the A&P does not find anything, insist the mechanic fly with you to try to reproduce it. If it continues to underperform, and the mechanic says nothing is wrong then consider finding a different plane to rent.
 
""""§ 91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include -"""

Did you familiarize yourself with the Textron Cessna 172S TCDS?

zSsnAv.jpg
 
I prefer to do a short field take off when I’m not in soft stuff to do a full static run up before releasing brakes... this gives you a chance to check for full rpm one last time before you are rolling.

Another option could have been when you got a bit more drop than usual was to lean her out and run her up full rpm to clean any lead fouling...

I would agree the most constructive criticism we all could give was one either to have aborted as you said you were close to the abort point not past when you noticed, and. Definitely would have been best to return to the runway ASAP once you noticed in the air something was off. Don’t get away from that runway if things aren’t right.

Glad all turned out okay for ya!
 
Dana said:
"So what is the 50/70 rule? It's a general rule for GA aircraft that says if you haven't reached 70% of your takeoff speed by the time you've reached 50% of the length of the runway, you should abort your takeoff."

Hah! If I'm not off the ground and climbing at 50%, something is very wrong...
Click to expand...
If you use it with respect to your actual takeoff distance it works quite well. Unfortunately most pilots are blissfully unaware of how much runway they use and how it compares to book distance.
 
I subscribe to the gold brake and check static RPM before rollout and so it every time unless I get a no delay. Gives you one more chance to verify the static RPM, it also helps in summer where you can lean until you get max performance before rollout. Some say it damages the prop, donno May be it does May be it doesn’t
 
I once had a malfunctioning ignition switch, that when placed in the "both" position, sometimes was only allowing the left mag to function. My run-up/take-off/climb was exactly as you describe.
 
WannFly said:
I subscribe to the gold brake and check static RPM before rollout and so it every time unless I get a no delay. Gives you one more chance to verify the static RPM, it also helps in summer where you can lean until you get max performance before rollout. Some say it damages the prop, donno May be it does May be it doesn’t
Click to expand...

ah... hold brake?
 
Sounds like something was up, like maybe a one mag takeoff? Reading your post it seems like you pressured yourself into taking off. The only feedback I can offer is don't ever hesitate to abort a takeoff if things aren't right or you don't feel like they're right. When in doubt close that throttle and taxi back to the ramp to figure things out. With a takeoff clearance that runway belongs to you, if you have to abort, landing traffic can go around and those waiting to depart can wait a little longer.
 
I had something similar in a rental years ago. Run-up normal and all is well after rotation until the point of no runway remaining, then the engine bogged down and all I could do in the 152 was hold at 400 AGL. Turned out something in the left mag let go after rotation.
 
mryan75 said:
My answer:

Mag drop difference: meh.

On the takeoff roll, I call (in order):

1. Oil pressure in the green

2. Generating proper power

3. Airspeed alive

If I'm generating less than full power, abort.

Lastly, it's better to go off the end of the runway slowing down than it is to stall it into the trees. To me there is no "V1" in a piston single. If I have any reason to believe it ain't gonna fly like I'm expecting it to, I'm staying on the ground, come what may.

There's a video out there somewhere of a Mooney going full power right into an embankment at the end of the runway. Fatal. It was clearly struggling to get off the ground during the entire takeoff roll. Might have had a chance if he'd decided to bag it and just accept he wasn't flying that day.

If you're struggling to get off the ground, pull the power and get on the brakes.
Click to expand...

I'm in this camp. For #2 I check the seat of pants feeling (thrust) as well as RPM/MP (depending on fixed pitch/CS prop). My departure brief calls for abort and land ahead for 'any issue' when there is runway remaining.

I've had to abort due to engine power once. It was a 2-3 second hesitation before returning to appropriate power after a full advance of the throttle. I actually maintained full power to about 30 - 40 kts IAS before I aborted. I was on a 8k runway so lots of room. Could have been nothing - could have been something.
 
IK04 said:
Next time choose a better title for your post.

"my most recent flight" would not have been so disturbing.

Nobody wants to imagine what the post was about with this title!
Click to expand...

I second that. When I read the title I wasn’t sure what the post was all about and assumed to worst
 
idahoflier said:
Sounds like something was up, like maybe a one mag takeoff? Reading your post it seems like you pressured yourself into taking off. The only feedback I can offer is don't ever hesitate to abort a takeoff if things aren't right or you don't feel like they're right. When in doubt close that throttle and taxi back to the ramp to figure things out. With a takeoff clearance that runway belongs to you, if you have to abort, landing traffic can go around and those waiting to depart can wait a little longer.
Click to expand...

Excellent point. Don’t think you have to take off just because you have been cleared. I have aborted more than one take off due to trivial things. I remember once right after rotation the MFD went blank, the first thing that crosses my mind was what else is going to fail ? i landed ahead and come to think of it I didn’t even have clearance, I told them aborting after my mains touched. Tower didn’t care, I taxied back and it was just the nav card came off loose. The point is I had no idea what else could have happened or why the MFD went blank or. If there are other impending electrical problems. I figured it’s best to sort it out at zero knots. You landed safely that’s what it matters, but for future food for thought.
 
Absolutely know and look at the engine rpm at the start of the takeoff roll for each plane that you fly. If you are not making the normal rpm, something is wrong. Since climb is dependent on EXCESS power, the loss of even a little power (or rpm) will dramatically lower climb rate, maybe to zero, so a good reason to abort a takeoff.

One insidious cause of partial power loss is loose baffles in the muffler. You can't really spot this in preflight, and it can come and go as the loose bits shift around and partially block exhaust flow. I had this happen in my AA-5 and it took a while in the shop to find the cause.
 
Thanks to everybody for their replies. I don’t mind the blunt criticism, that is the kind that sticks and I cannot refute much of it. This event and your feedback has prompted me to re-evaluate my ADM processes, which I think was overdue anyways. Many lessons learned that will never leave me.

I stopped by the A&P today, and there was a problem with the engine after all. The magneto timing was off, causing an unised fuel build-up in the cylinders. I did have fouled plugs.
 
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Hi danman999. I wanted to privately ask you about the plane? Maybe you can change your "privacy" setting to allow "conversations" from members? Joe
 
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