KE5BM
Pre-takeoff checklist
Good Day! I'm a low-time pilot, less than 100 hours having just earned my certificate in April 2023. Last week, I reserved a C172 from the FBO at my home field. It was the kind of day VFR pilots wish for. CAVU, -1800 density altitude, about 40°F and 60% humidity. I was planning on doing a couple hours in the air with some air drills, work on my landings and get some aerial surveillance of a treacherous inlet that has shifted quite a bit after two strong storms had blown through. I offered up to my crew if anyone wanted to go along they were more than welcome and to no surprise, one of our newest crewmen who'd reported less than a week prior wanted to go for a ride. Perfect! He's going to be a boat driver so I can show him from the air some of the waterways of most concern.
About two hours prior to my flight, the FBO called and asked if I'd be willing to take a different aircraft. They had originally scheduled me with the 1963 model C172D that every student here seems to prefer and someone wanted to get a lesson in last-minute. No worries...5 planes to choose from. They offered me the C172K that I did most of my training and my checkride in. I like that plane better anyway so no worries. Now, this time of year the planes aren't getting worked near as much as they do in the summer. During the summer months, the rental fleet is doing triple duty between training, aerial tours, and rentals. In the winter it's mostly on-demand. So, being the prudent guy I am I looked up the ADS-B records to see the last time my plane had flown. The night prior, it was brought over from Nantucket after some minor interior work had been done.
When I arrived at the field, my plane was still in the hangar so I assisted the FBO agent with pulling her out and proceeded to start my preflight. Tanks were full and everything seemed in order. Mistake #1: For whatever reason, when I began my flight training over 20 years ago I was never shown how to drain the engine sump to check the fuel. I had only recently been shown how to do that AFTER I got my certificate. So, I'm still working on making it a habit in my pre-flight to pull that plunger. This day, I neglected to do it. I did check the tanks and all looked blue and bright. My passenger arrived, we talked for a little bit and I took some time to talk about what was inside the aircraft and answer any questions. We had all the time in the world until sunset so I wanted to make sure all his questions were answered and he was comfortable flying with me. Once satisfied, we fired up for this aircraft's first flight of the day. I stayed on the ramp for a bit letting everthing warm up and go through my interior pre-flight. Seeing no issues, I taxied to the active runup. I went through the runup with no issues. Magnetos did what they're supposed to do and the carb heat did what it's supposed to. Again, I'm pretty familiar with this plane so if something was off I'd notice pretty quickly. Waited our turn and once the runway was clear we applied power for takeoff. Even before Vr, the plane seemed to want to jump into the air. This particular plane has a STOL package installed so the early lift can be a little deceiving. At rotation the plane just wanted to eat the sky. I was remarking to my passenger about how high an angle we had for Vy when the engine stuttered a little bit and I lost about 5 degrees of AoA almost immediately. "Must be carb ice," I said as I pulled heat. I had only once before seen carb ice while I was doing some night IFR training with my CFI a few weeks before. That onset seemed a little more subtle but given that conditions were almost perfect and the engine hadn't really reached full operating temperature I (Mistake #2) assumed it must be ice. I pulled heat and for a second it seemed better but it just didn't seem like it was clearing. So I called for a precautionary return which got the A&P's attention on the ground and asked if I needed anything. "I'm good, just think I have carb ice but not 100% sure. I'm gonna come back down and go through some checks just to be sure." Got back on the ground with no trouble...actually quite a nice landing compared to how I've been lately. Taxied back to the runup area. A&P says to me the conditions are right for icing and I asked if anyone else had reported any. None that he was aware of. Three other planes in the area as well and nobody said they had iced.
So I get back to the runup and start to go through my checks again. Up to 2000 RPM this time, pull heat (mistake #3) but didn't cycle the magnetos. I'll just try this takeoff with heat in and see what it does. Couldn't replicate on the ground and everything's running smooth now. Back on the runway and here we go with carb heat on for good measure. I reach my decision point and I'm just now reaching Vr (which is way late) and (mistake #4) decide to rotate. I look at the tach and I'm running a little over 2100 RPM. WAY too low. So I close carb heat, engine picks back up and I'm climbing at normal Vy again. For only a moment. At about 700 feet, the engine stutters again but it feels like I hit the brakes. Actually, it felt more like when you full prop pitch before your RPMs are low enough. I said "nope, I don't like this" and called my return again. A&P comes back on the radio. I tell him, it's not acting like carb ice. I can't seem to get it to clear so I'm just gonna bring it back. I made a tight pattern and came it a bit fast. OK, real fast. I was about 90 knots at the numbers. I floated about 1000 feet but got it down and stopped well before the end of the runway. Taxied back to the ramp where the A&P owner and a friend of mine who works part time came out to meet me. I explained everything I did and they told me it's no trouble and they'll look under the hood. I even asked one of the CFIs working that day if they'd seen ice and they hadn't.
I left the field torn. I felt ok with my decision to get on the ground because regardless of the issue, I didn't feel I was making the right adjustments to fix the problem so I was quickly getting behind the plane. At the same time, I'm thinking maybe I'm just paranoid...I need to work on my engine management in the future. Maybe it was water? I failed to check the engine sump. Maybe it WAS ice and I just didn't let carb heat do it's thing. This flight was right before Christmas and the weather turned nasty for several days so I'd been waiting patiently (anxiously) to see if the plane went back up.
This morning, I checked ADS-B and saw the plane was up. It was returning from a short cross-country flight. I texted my friend at the field "I guess nothing was wrong. I see she's back up."
"Actually, no" he says. "Turns out a very unusual magneto gear shaft failure. Two shafts: one drives the main gear into the engine. The second is a small shaft & gear that opens and closes the points. That one snapped clean off. So you were running on one mag. I think (owner) took a pic when we took it apart."
So, good news is I wasn't crazy. Bad news is, I made a few mistakes that could have resulted in a worse situation and/or could have helped with troubleshooting. So here's what I've learned:
1) Don't skip the engine sump. After this I'm certain I won't need to intentionally remember to do it anymore.
2) When doing a runup, follow EACH item, EVERY time. There was a reason I was back on the ground. The engine wasn't happy for some reason and I didn't take the time to check everything I could before attempting the flight again. I'm certain that if I had cycled the magnetos again, the one that had just begun to fail likely would have alerted me.
3) Your decision point should be CONCRETE. If everything doesn't look 100% correct, pull power and hit the damn brakes. Don't question why everything isn't 100% as you rotate.
My log for the day indicates 0.4 hours. But I'm here to tell you, I learned more in those two trips around the pattern than I did on my two 3-hour cross country flights. Open to suggestions/critiques/comments.
About two hours prior to my flight, the FBO called and asked if I'd be willing to take a different aircraft. They had originally scheduled me with the 1963 model C172D that every student here seems to prefer and someone wanted to get a lesson in last-minute. No worries...5 planes to choose from. They offered me the C172K that I did most of my training and my checkride in. I like that plane better anyway so no worries. Now, this time of year the planes aren't getting worked near as much as they do in the summer. During the summer months, the rental fleet is doing triple duty between training, aerial tours, and rentals. In the winter it's mostly on-demand. So, being the prudent guy I am I looked up the ADS-B records to see the last time my plane had flown. The night prior, it was brought over from Nantucket after some minor interior work had been done.
When I arrived at the field, my plane was still in the hangar so I assisted the FBO agent with pulling her out and proceeded to start my preflight. Tanks were full and everything seemed in order. Mistake #1: For whatever reason, when I began my flight training over 20 years ago I was never shown how to drain the engine sump to check the fuel. I had only recently been shown how to do that AFTER I got my certificate. So, I'm still working on making it a habit in my pre-flight to pull that plunger. This day, I neglected to do it. I did check the tanks and all looked blue and bright. My passenger arrived, we talked for a little bit and I took some time to talk about what was inside the aircraft and answer any questions. We had all the time in the world until sunset so I wanted to make sure all his questions were answered and he was comfortable flying with me. Once satisfied, we fired up for this aircraft's first flight of the day. I stayed on the ramp for a bit letting everthing warm up and go through my interior pre-flight. Seeing no issues, I taxied to the active runup. I went through the runup with no issues. Magnetos did what they're supposed to do and the carb heat did what it's supposed to. Again, I'm pretty familiar with this plane so if something was off I'd notice pretty quickly. Waited our turn and once the runway was clear we applied power for takeoff. Even before Vr, the plane seemed to want to jump into the air. This particular plane has a STOL package installed so the early lift can be a little deceiving. At rotation the plane just wanted to eat the sky. I was remarking to my passenger about how high an angle we had for Vy when the engine stuttered a little bit and I lost about 5 degrees of AoA almost immediately. "Must be carb ice," I said as I pulled heat. I had only once before seen carb ice while I was doing some night IFR training with my CFI a few weeks before. That onset seemed a little more subtle but given that conditions were almost perfect and the engine hadn't really reached full operating temperature I (Mistake #2) assumed it must be ice. I pulled heat and for a second it seemed better but it just didn't seem like it was clearing. So I called for a precautionary return which got the A&P's attention on the ground and asked if I needed anything. "I'm good, just think I have carb ice but not 100% sure. I'm gonna come back down and go through some checks just to be sure." Got back on the ground with no trouble...actually quite a nice landing compared to how I've been lately. Taxied back to the runup area. A&P says to me the conditions are right for icing and I asked if anyone else had reported any. None that he was aware of. Three other planes in the area as well and nobody said they had iced.
So I get back to the runup and start to go through my checks again. Up to 2000 RPM this time, pull heat (mistake #3) but didn't cycle the magnetos. I'll just try this takeoff with heat in and see what it does. Couldn't replicate on the ground and everything's running smooth now. Back on the runway and here we go with carb heat on for good measure. I reach my decision point and I'm just now reaching Vr (which is way late) and (mistake #4) decide to rotate. I look at the tach and I'm running a little over 2100 RPM. WAY too low. So I close carb heat, engine picks back up and I'm climbing at normal Vy again. For only a moment. At about 700 feet, the engine stutters again but it feels like I hit the brakes. Actually, it felt more like when you full prop pitch before your RPMs are low enough. I said "nope, I don't like this" and called my return again. A&P comes back on the radio. I tell him, it's not acting like carb ice. I can't seem to get it to clear so I'm just gonna bring it back. I made a tight pattern and came it a bit fast. OK, real fast. I was about 90 knots at the numbers. I floated about 1000 feet but got it down and stopped well before the end of the runway. Taxied back to the ramp where the A&P owner and a friend of mine who works part time came out to meet me. I explained everything I did and they told me it's no trouble and they'll look under the hood. I even asked one of the CFIs working that day if they'd seen ice and they hadn't.
I left the field torn. I felt ok with my decision to get on the ground because regardless of the issue, I didn't feel I was making the right adjustments to fix the problem so I was quickly getting behind the plane. At the same time, I'm thinking maybe I'm just paranoid...I need to work on my engine management in the future. Maybe it was water? I failed to check the engine sump. Maybe it WAS ice and I just didn't let carb heat do it's thing. This flight was right before Christmas and the weather turned nasty for several days so I'd been waiting patiently (anxiously) to see if the plane went back up.
This morning, I checked ADS-B and saw the plane was up. It was returning from a short cross-country flight. I texted my friend at the field "I guess nothing was wrong. I see she's back up."
"Actually, no" he says. "Turns out a very unusual magneto gear shaft failure. Two shafts: one drives the main gear into the engine. The second is a small shaft & gear that opens and closes the points. That one snapped clean off. So you were running on one mag. I think (owner) took a pic when we took it apart."
So, good news is I wasn't crazy. Bad news is, I made a few mistakes that could have resulted in a worse situation and/or could have helped with troubleshooting. So here's what I've learned:
1) Don't skip the engine sump. After this I'm certain I won't need to intentionally remember to do it anymore.
2) When doing a runup, follow EACH item, EVERY time. There was a reason I was back on the ground. The engine wasn't happy for some reason and I didn't take the time to check everything I could before attempting the flight again. I'm certain that if I had cycled the magnetos again, the one that had just begun to fail likely would have alerted me.
3) Your decision point should be CONCRETE. If everything doesn't look 100% correct, pull power and hit the damn brakes. Don't question why everything isn't 100% as you rotate.
My log for the day indicates 0.4 hours. But I'm here to tell you, I learned more in those two trips around the pattern than I did on my two 3-hour cross country flights. Open to suggestions/critiques/comments.
