Rough Engine- Was It Carb Ice Or Vapour Lock?

[@JohnUllrey]

Very well done good sir! The data from your glass panel is really an amazing thing to have. My dad was an Air Force Navigator and he liked to say: "You never want to run out of Airspeed, Altitude, or Ideas at the same time."

[@DannyCreech]

Good job Glen. I shared this video with a former Student of mine who owns an older C-172. Also, very smart move kicking that CFI out of the aircraft and never flying with him again for saying the POH is always right. That is a stupid CFI.

[@goldierides9481]

Thank you. I'm training in a 1960 Skyhawk, ready to take my check ride. I was unaware that this could be an issue, and I have always run on both.

[@TJF8]

For us non pilots, I had to look up POH. Pilots Operating Handbook. Great video. I admire your transparency, how your research and your attention to detail.

[@joeyhardin1288]

thanks

[@MSI2k]

I couldn't even keep my cool when my tire disintegrated on the 401 express... hats off to you for not panicking high up in the air. Stay safe, Glen.

[@zoe..d]

Peefect display of top level airmanship on display here. Not afraid to deep dive into a situation regardless of preserving ones own reputation. The goal is learning, making well informed decisions about changes required. Highlighted the issues surrounding increasing irrelevance of aircraft documentation as modifications become a part of your plane. Last but not least, you were able to communicate this extremely clearly so others will go home safely. Bravo Sir.

[@togadriver]

Thanks Glen. I own a 1957 C-172. I flew it for the better part of 500 hours in many conditions before experience vapor lock. I have experienced it twice, and both occasions with the tank on both above 5000 feet. I think you’ve given the best explanation here that I have seen. A few points to add. I could not understand the mechanism of what would cause the vapor lock and how switching to single tank operation somehow made it better. According to the folklore on the Internet, Cessna apparently tried using glass tubes to see if they could replicate the problem and supposedly could not. After some consideration, I believe that’s probably true. The fact is that glass tubing does not conduct heat nearly as well as the aluminum fuel lines do. By switching to single take operation, you are effectively doubling the fuel flow through the tubing between the fuel tank and the fuel selector, thus allowing less opportunity for fuel bubble vapors to form and if they do, flushing them out of the system quicker. Thanks for your videos and helping us fly safely!

[@GingerThePlane]

Very timely episode, we recently had a student pilot experience what’s likely to be carb ice here at KBLI. It resulted in a forced landing in a nearby field, she did wonderful and both pilot and plane will fly another day. Thanks for the reminder, carb heat and fuel management is simple in a 172 but should never be taken for granted. 👍

[@MrDdaland]

Well, you answered one thought I had (Mogas and possibly getting gas with ethanol) Main thing is- you had TIME to work through the problem. You kept flying the aircraft, you had a plan for landing in case you needed, and kept your head while trying to analyze the problem Well Done!

[@davidpodbury8415]

Great video. My dad flys and 1956 172. And we fly a 1962C 172. We always go to single tank operation above 5000 feet. Never have had a problem. So I stick to it. People will always want to argue, but I listen to the old pilots around me.

[@kazflight]

Thank you for sharing! I would have never thought about vapour lock in anything carbureted, I've been taught that it only applies to fuel injected engines. Excellent reminder about the static nature of POH's. Great job on the cause check, glad to see you were able to land safe and continue your flight.

[@MrDdaland]

Lol, never owned a old Ford tractor? Fuel line goes between exhaust manifold and block- you can see the fuel boiling out from the tank outlet

[@XMarkxyz]

I think this is one of the best video's you've made, first because it's always somewhat hard to admit having an issue (even though I wouldn't say it was your fauld and you come out of it really good), second because it was very informative and might turn out useful to people who risk having the same issue and also because we as humans learn something new when something unexpected happens. So by all means well done. By the way my guess is as good as everyone's else but I'd say it was vapour lock by the evidences you show us. I don't know how youtube actually works, I mean who does, but maybe you might add the plane's model and year to the title too so people with the same model can find the video more easily, just a suggestion.

[@richterdfr]

Hello Glen, You are on the right path. You might read Bob Hoover's autobiography noting how cautious he was. For instance he would take up to one hour to pre-flight his aircraft. His flying career was marked by attention to detail in all aspects of the flight. I really was in awe as I read his book. Have you heard that saying " There are old pilots and there are bold pilots but there are no old, bold, pilots "? I was a student pilot here in San Diego from 1973-1979 and a flight instructor from 1979-1984 and the number of pilots who died during that period, age 24-35yrs, that I knew exceeded the number that I knew who died of other causes. Now than I'm 74 yrs. things are different of course. Second comment: Have you thought of adding wheel pants to your aircraft? You could paint them solid red. They would look really good and you would burn less fuel. Have a great day.

[@richardcox5302]

Awesome video. I got carb icing in my 172B over Honolulu once at 2000ft about 1 mile away from some moisture in the air. I had difficulty maintaining the cleared altitude of 2000ft through the Class B airspace so I turned around and RTB at Kalaeloa. While descending out of 2000ft I pulled the carb heat and the engine started running smooth again. I found out later from my mechanic that as the air goes through the carburetor the temperature drops about 30 degrees, which is how you can get carburetor icing in 70 degree weather in Hawaii. Scary lesson to learn while flying over a metropolis like Honolulu.

[@orvjudd1383]

Great critical thought processes. The FAA is a bureaucracy. Made up of humans who make mistakes. I would feel comfortable flying with you any time.

[@MeMe-Moi]

I'm not a pilot, but this is a good framework for any issue in any industry 1. Know your environment (your actual environment, not the environment "the book" says you have) 2. Know your likely problems 3. Have a plan for avoiding those problems 5. Know what to do when those problems happen anyway 6. Have a plan for post incident investigation 7. Implement the lessons learned from the investigation into your procedures going forward to reduce the risk load.

[@sharlenezuhlke1561]

Hey Glen, I saw a picture of you with MVU at the Give Hope Wings airfield! So exciting! I was afraid the wildfire’s might be an issue but everyone in the pictures look happy. It will be great to hear of it when you return. Go Team!

[@321southtube]

You kept your head. You continued to aviate. You set yourself self up for a landing (if needed) and continued to troubleshoot. You cleared the issue and continued your trip. You're here to pass on some valuable information. Win...win...win. Well done.

[@KriLL325783]

Outdated information being held as gospel is such a big issue in a lot of fields, because it was printed a long time ago and either people don't know it's not correct anymore, or the official process to update/amend it hasn't caught up etc.

[@Kinkajou1015]

I love how authentic you are, going over the event and having a humble heart to heart about what you believe the root cause was and the resolution. Much better than intentionally bailing out of the plane and letting it glide without anyone at the controls.

[@jtstuff2981]

Wow! This just happened to me in my 1961 172C!! Clear day 7500', 2300 rpm, leaned a bit, on both tanks running great. Then the rpms faded and it nearly died. I did the same as you, carb heat on mixture full rich... I throttled back and luckily was over KRBG. I began descending, engine idling fine with carb heat on...at 4000' I wanted to test it, full power full rich, carb heat off...again not good. At that point I circled and landed. A&P cleaned the plugs, replaced 3 of them and I flew back home no problem. I was not aware of the >5000' single tank AD. I wasn't aware that carb ice can happen at 2300 rpm, my home A&P thinks I was too running ROP and it fouled my plugs...or was it vapor lock? Either way, I've learned a lot in the past few days! Thanks Glen!

[@GlensHangar]

I'm glad that I could help!

[@alanbuller3371]

Great video. Although I am not a pilot, I find the channel very interesting, informative, and entertaining. Keep up the great work. PS, the people of Brechin might not be happy that you added an 'L' to the name of their quaint little town 😀.

[@mikes5032]

Thank you for sharing your story. I agree that many pilots will far too often use the POH/AFM as a crux, with the completely incorrect belief that it is infallible and that 50-70 years of advancement and better understanding is irrelevant. One small nitpick.... it's Brechin, not "Brechlin" (no 'L').

[@johnhanes5021]

Thank you for sharing your experience. Experience is the best teacher. On our own the valuable lessons come right after we needed it the most. Best to learn from those who have gon before us. Again Thank You.

[@Steve-eo9iy]

That was a thoughtful, honest, well researched presentation that should help others. I also commend your willingness to talk about it fully with your viewers. I believe many would, understandably, not want talk about it, never mind going on KZbin. This video also gave me a chill as I thought back to a carb ice issue I had several years ago that I luckily detected before takeoff. Cheers

[@richardgreen6857]

My hangar mate has a '61 Skyhawk...I'm going to share this video over to him! His son is working on his commercial in the airplane! As an aside, too many newish instructors really think that rating gives them a lot more knowledge than they actually have, particularly regarding the performance of an airplane which the owner knows and has researched intimately...

[@LikeOnATree]

Great video Glen, thanks for sharing your story! It’s valuable when pilots share situations like this to help other pilots, it’s crucial for safety. We all have situations, make mistakes, etc and hiding that helps no one. Sharing experiences helps everyone. I have heard the “…wind your watch” statement before and it’s true. Take care of any appropriate immediate action items, then take a moment and assess things. That moment can help you deal with the initial startle of a problem and can improve decision making. Thanks again for sharing, glad you had a good outcome!

[@quarlow1215]

Bravo for putting your ego aside for the sake of betterment to the sport at the risk of your own humility. But from watching both your channels over the last couple of months its clear that you don't have a large attitude. I don't fly but my best friend is a commercial pllot and you you both know your syuff and stick to your stuff. I would fly with you any day.

[@172GV]

We own a '61 172B as well. I have flown it for 20 years and not had a similar issue. Then last year it happened 2x in 90 days at 7500 feet in moderate IMC conditions. We did an identical investigation and came up with identical conclusions. Additionally we had engine, fuel caps and fuel tanks all checked out to be 100% sure we ruled out all other possible causes. We are 90%+ sure it was vapor lock both times. You comments about POH and checklists are 100% correct as well. Without wing extensions the stall / break is much lower than the POH indicates. It has baffled a few CFIs over the years that the stall is so low. Usually they give up and tell me to recover when the horn sounds.

[@werelemur1138]

My late great-uncle owned a Cessna (not sure which one but I know it was a four-seater because my sister, my dad, and I went up with him a few times) from the 70s to probably the early 90s and I know I heard of vapor lock from listening to him talk with my dad and other family members. I don't understand people who refuse to understand that knowledge increases over time, and the best information available in the 1960s may no longer be current in the 2020s.

[@chrisjohnson4666]

Is there a way your dynon can give you a reminder if you get to 5000ft it will issue a master alarm switch to one tank...If you forget at cruse... Also did the dynon give you a master alarm or anything that the engine was running out of normal parameters??? GREAT VIDEO... You and Blancolierio need to get together someday...

[@GlensHangar]

The Dynon throws a bunch of warnings (audio and visual) for when different specific engine levels are out of parameter, and it does it on screen with different colours depending on severity (grey, yellow, red). It doesn't have a warning for switching to one tank when reaching 5,000 ft, but that's burned into my brain at this point.

[@christiandrouetdaubigny2127]

Had the exact same thing happen in a 1965 C172 (N8800U) 25 years ago, lucky it also ended well.

[@gerardacronin334]

This is a wonderful PSA by a responsible pilot.

[@N519MP]

Thank you for sharing your story. I too experienced this issue in a 66' G model. Once during my solo cross-country at 6500' DA, and a second time during a cross-country at 3500 PA. The first time was extremely unnerving being I was a student and still learning. Luckily I had great instruction and followed my emergency procedures, which includes swapping to single tank operation. As you stated swapping to the first tank did nothing to fix the issue. Upon swapping to the second tank she lit and all power was restored. As you stated there seems to be a lot of misunderstanding on this issue. After landing I called my instructor and discussed the incident. He wasn't positive of the problem so I started a full Google investigation into the problem. After many pages of reading and sorting through the opinions and getting to the fact, I came to the same conclusion as you. A combination of DA and auto fuel lead to vapor lock. I have a few documents from cessna that explain the issue. Also found a document published by the Canadian equivalent to the FAA that does a deep dive into the use of auto gas in aircraft and the reasons for developing vapor lock with its use.

[@GlensHangar]

That Transport Canada document should be required reading for anyone flying a legacy Aero engine on MoGas: tc.canada.ca/sites/default/files/migrated/tp10737e.pdf or even this one: tc.canada.ca/en/aviation/reference-centre/airworthiness-manual-advisories-aircraft-maintenance-manufacturing-branch-advisory-circulars/airworthiness-manual-advisory-ama-no-5499

[@RichWellner]

Thanks for sharing Glen. I'm workin on an edit right now from a couple weeks ago where a fly tried it's best to put me in a field.

[@GlensHangar]

Ha! Can't wait to see it.

[@derekroulston1977]

Interesting story Glen. I did my training on a 68 172 and we switched tanks every 20 minutes. Once done I bought a 76 and continued switching tanks until I was out with my CFI in my plane and he asked why I was switching tanks which is what he taught me. He then explained my plane was newer and we didn’t need to switch. 😀

[@russellworman2899]

Thank's Glen, I just bought into a 1969 172K. I will be looking!

[@billbrisson]

This is another example of knowing your aircraft! Lucky where you fly you have so many options for alternat airfields! Where I fly, (when I'm not flying floats) there are very few airfield options if I need to make a landing, so I'm always watching for a fields or stretch of road should the need arise

[@sip4751]

That CFI would have a "does not compute" moment if he/she had to fly a older piper product. Best glide? You figure it out? Grass take off distance? What's grass? Tail wind takeoff/landings? Crickets.... LOL.

[@mayberrywj]

Great video..... Good idea to first turn towards those two grass strips. Not only did you change your safety procedures and your checklist, I bet you changed your shorts too.....:)

[@paulmccool378]

Wow. Really cool video. I don't fly, but I did work in the auto repair business for a long time, so I really enjoyed the tech aspects of analyzing what caused your issue. Great stuff.

[@evangreenacre3172]

great video, even though i don't fly I was cleaning up a family members house, and found a Cessna 1966 Owner's Manual for Model 172 And Skyhawk, but it doesn't have anywhere near the amount of information those PoA's you were showing, But I'd be willing to mail it to you want to collect (like you do cooking books).

[@Blue_Camera_Cat]

Good on you for bringing this to light. I hope alot of CFIs see this!

[@danchain6152]

I also have a 1960 172b, and mine also drains the left tank faster than the right. My dad (former cessna design engineer) found an article explaining why they do this. Basically its because of the vent system. Interesting on the fuel system ad, ill have to dig to see if mine was done because i dont have the sticker

[@michaelmcauley6572]

Fantastic analysis and put in the back of your mind, another piece of data to have.

[@WingsOverTO]

Great video, Glen, thanks for doing that. Glad it all turned out ok for you!

[@shapeshifterboogie9853]

Not a pilot, still inspired. Great video Glen,

[@analicameron319]

Thank you for sharing! Informative information to share! Have a great day.

[@rogerrabt]

Back in about 1978 or so, my father and I were flying into SFO in a '59 182. It was stressful anyway! Fairly low over the water on approach, and the engine starts running rough. Carb heat on and a few seconds later it evened out. Worst place to have that happen, though. If it had been vapor lock or something worse, we'd have been in the water. Not much time to fix things.

[@thomashesselgrave6898]

I only experienced carb ice one time. Cessna 180, beautiful day, started losing mp and thought the throttle friction was loose so I pushed in the throttle and tightened the friction. Twice. Light bulb comes on and I apply carburetor heat. Power drops further and then gradually returns to normal. Then my pulse rate gradually returns to normal.

[@cmflyer]

That POH is a POS! Great story and lesson Glen!

[@jonathonboerema8886]

Amazing story and great reflecting and fact finding. Thanks for sharing.

[@Pupparazzi22]

Thank you Glen! I own a '59 C172 and I will be adding the fuel selector switch over to my cruise check list. Glad you were able to manage the situation and humbly (and informatively) share from the experience.

[@_FNQ]

Excellent debrief Glen. Many thanks for sharing.

[@AlphaWhiskeyAviation]

Fantastic information and I loved this video. Also that plane is gorgeous.

[@JoseRivera-lt2cc]

Great presentation - much needed reminder to know your own airplane. Model specific applicable issues 'could' bite you in the butt especially once upgrades/modifications (& AD's) have been implemented. Updated electronic checklist is a solid recommendation.

[@stubby4317]

Thanks for sharing. I have a 1963 172D. Was actually assembled in late 1962. My POH does address the issue of vapor lock. Perhaps it's a newer version of the original POH? Thinking about the issue with density altitude hadn't occurred to me. Very interesting.

[@johnfitzpatrick2469]

HINDSIGHT "what could possibly go wrong" Glen there's only one way to get experience, and you now have it. VIDEO PRODUCTION, 90/100 INVESTIGATION 78/100 ANALYSIS 79/100 I am curious, when the plane is fitted with breather fuel caps. The other thoughts were engine heat vaporising fuel in the line/filter. Overall a good performance Glen keep up the good work. 🌏🇭🇲

[@pastorrich7436]

An EXCELLENT and informative review. Thank you!

[@cameronmolt5649]

Interesting. I was a 9500' in a 172G. Same thing happened to me. Hard to say if it it was carb ice or VL. I applied carb heat and switched tank. The engine came back to life and i went on my way.

[@stephenmccarthy6892]

Thanks Glen, this was really interesting and informative to someone who wants to buy a 172

[@randellino]

Woah, glad you are safe.

[@berniebrown9115]

Super post. Just love your reasonable thought process

[@garputhefork]

13:13 Arguing with the pilot sounds like a great way to wind up walking home from a field in the middle of nowhere.

[@henryverbruggen5001]

Great video Glenn. I own a 172E.

[@bokkenka]

Great video! I don't fly, but I was still riveted to the screen.

[@rebeccahartsfield9986]

I’ve watched videos on your other Chanel as well, you mentioned going to Arkansas to visit family (I live in NW Arkansas btw) are you flying yourself,with stops along the way. I’m curious how it works flying over international lines in a small private plane. It would make for interesting viewing IMO. Safe travels and really enjoy the videos. 👍

[@sharlenezuhlke1561]

Great video! Thank you so much for the vulnerability. That is why we can trust you. SO glad you are smart and safe!

[@melissalaberge4683]

Extremely helpful, thanks for sharing!!

[@laszlovasko]

I don't believe it was vapor lock. Temperatures weren't conducive to vapor lock. However, excellent video, and it raised a lot a questions. I have a Cessna 170 - and was puzzled why the AD didn't apply to the 170s. Searching on the 170 forum - others have asked the same question years ago. Here's an excerpt from a discussion with Cessna tech support in 2002: "I just got off the phone with Cessna Technical Rep. Tim Fischer who had consulted with the retired Cessna Rep. responsible for developing this procedure that responds to the AD 72-07-02. Here's their answer: The airplanes that experienced problems were later model Lycoming-powered 172's. Although with an altered fuel system which included short vent lines connecting the fuel delivery pipes to the fuel vent pipes, the problem continued. Although the factory was unable to duplicate all the symptoms reported by some operators, they did develop this procedure which eliminated all further complaints. (The Lycoming engine's greater fuel consumption may have contributed to a lowered head pressure in a system primarily designed for the C145/O300 engine.) Although none of the Continental-powered airplanes suffered from the problem, Cessna thought it conservative to include them in the AD note. (After carefully listening to the development of the conversation, I suspect it was to avoid casting dispersion upon their newly selected engines of choice, since Continentals would no longer be offered in the 172. In other words, they were not going to go back to the Continental as they'd bought over 4,000 Lycomings and had them in stock, so in order to not make it look like they'd selected a troublesome engine, they were anxious to make it apply to all previous aircraft. My own suspicion.-gh) Even though the straight 1956 model 172 has exactly the same fuel system as the 170B none of the taildraggers ever had any such problems. (Nor in fact did any of the Continental 172's.) Proving this point to the FAA would cost Cessna a lot of time and money on airplanes no longer manufactured. Cessna took the easy way out with the FAA." Interesting issue. I suspect you had carb ice, as conditions were conducive for it, although your experience switching between tanks gives me pause. Who knows! What's great, is posting videos like this to get people to better understand their airplane, obscure ADs, etc. Note that assoicated service letter SE72-7 states that if you are running on both tanks, and experience fuel starvation issues, to switch to either single tank for 60 seconds, then switch tanks. I wasn't aware of this (as I'm sure most pilots aren't). So to cover all bets - maybe it's worth to switch tanks when encoutering engine roughness in addition to carb heat on these machines ....

[@GlensHangar]

Of course you are entitled to your opinion, but every expert I've shown the engine logs to agrees that it wasn't carb ice - based on carb temps, and other indicators. They all agree that it was a fuel starvation issue, and most likely vapour lock. You mention temperature wasn't conducive to vapour lock - temperature is only one factor that can create vapour lock, and it's a common mistake to believe that it is the only factor. When in fact turbulence, and pressure also cause vapour lock, and that's what is at play in this fuel system. As for the post from the 170 forum... I've read it, and read variations of it on other forums from different posters. Problem is: it's all conjecture and here-say, with the original poster admitting it's also based on his own suspicions. The post also makes bold statements about Continental engined 172s, that from accident reports seem to be factually incorrect. I asked the experts who reviewed my engine logs about this post and they all said essentially the same thing: whoever wrote it was just spewing bs to hear themselves talk.

[@amyeagleton697]

Thank you for sharing, glad you're safe! Do you think you'll ever take the time to re-plumb, or just stick with the sticker?

[@beaver6d9]

Fascinating and glad you used all your skills to make it out ok.

[@danretief4363]

Thanks very much for a very informative video!

[@jeffgerndt2813]

Good video! Thanks.

[@NFvidoJagg2]

for anyone looking to compare the two fuel system diagrams 5:10 and 14:27

[@bobwilson758]

Early in video I was going to ask you about vented fuel tank caps …. Good ! Thanks - Also , I like your aircraft ! See ya

[@larry1873]

Good Job

[@wolfkin73]

Ive got 300 or so hours in early 172s over 30 years. I have to say i have never experienced vapor lock in one. Carb ice plenty of times. I have had vapor lock in other aircraft ( usually above 8000 feet) every time decending 2000 feet or so immediately fixed the roughness. I think looking at your graphs the reduction of fuel flow was the result of the power loss not the cause.

[@GlensHangar]

Could be - but some of the top mechanics / engineers in piston engine aviation have independently reviewed the data and would disagree with your thinking.

[@sey1yes2]

Very informative.

[@turtlehopper81]

Glen, I'm not a pilot, I'm a station programmer and studio technician for 2 local television stations. Anyways... I came from the cooking channel and started binge watching all of the Hangar videos. The plane looks great by the way, I'm very fascinated by the glass panel I had a couple questions. How did the plane get the call letters of C-FMVU? Did the plane always had those letters? Are those the letters that the airport towers sees on their radar? Anyways, this fascinates me so much.

[@GlensHangar]

That’s the registration right from when it rolled out of the factory in 1960. The registration mark will stay with the plane until it’s removed from service, then the reg will go back in the pool for another plane.

[@connervital]

I had a issue with my 61 172b with sticking valves. It would drop rpm until I would lower power and then it would go back the normal. It took for ever to figure out because it was not consistent

[@alanmoberly64]

Very well done video very informative and I am not a pilot.

[@alpenglow1235]

Although I watched only until 15:00, my comment is this: The only fuel pump in your Cessna is the primer. If you gave it a few pumps and the engine responded affirmatively, what would that tell you?

[@rcmerrill1]

The book you have for your 172 is an owners manual, not a POH. The POH and it's required use was mandated in the early 70's.

[@GlensHangar]

Regardless of the semantics of what the book is called (Owners Manual Vs POH) they serve the same purpose and contain the same operating information about the aircraft. Under Canadian Air Regulations, I'm required to carry it in the plane, in a place that is readily reachable while in flight.

[@GaryMCurran]

Great video, Glen. Do you have a Carb temp sensor for the Dynon? If not, are you going to install one? They do have one, I just checked, although I don't know if it's available for your engine. At least that way you would know if the temps in the carb were in the danger zone. I think you did well, you kept your head about you, you worked the problem, you found a solution, and you were able to get on the ground and check things out before proceeding.

[@Hooknspktr]

I have a '66 G model and the POH (which I ordered a few years ago) mentions nothing about vapor lock. I also have an old tattered copy of the '67 H model POH and it DOES have a nice detailed description of vapor lock (at the end of Section 1) on single and both tanks along with how to avoid it and how to clear it if it happens. I do not know if it was a later issue version with an update or if it included it in the original 67 issue. Perhaps someone with more knowledge can shed some light.

[@CFITOMAHAWK2]

Some carb heat and some mixture lean cures most partial power. But it takes 20 to 60 seconds. My CFi Had 3 of those.

[@GlensHangar]

Yeah but based on the way fuel flow trickled to a near stop - the problem was far from the carb and engine.

[@AvgDude]

If you run mogas in your plane, be aware that Winter blend gas doesn’t do well on warm days at altitude. Your fuel will start vaporizing in the lines.

[@GlensHangar]

Yep - no mogas in the plane.

[@kmg501]

Doesn't the manufacturer issue a updated POH?

[@sharpe3698]

Isnt the way that the POHs work/are supposed to work, that pages get updated/replaced/added with updated information when things auch as directives change? I'm guessing that's wrong, and I dont actually fly, but the POHs ive flipped through for flight simming often have addenda and such

[@eiselbay]

Great video as always. Vapor lock is no joke. I was really wondering why there is a consensus that not many people comply with th AD's as they are mandatory. Unlike service bulletins which are nonmandatory, the IA/A&P can't sign airworthyness off unless the AD's are complied with per the FAA. Is the TCCA different? I'm almost done with A&P and I'm wondering if there is some sort of situation I don't know of that could allow this.

[@GlensHangar]

In this case the AD had two parts and you could comply by doing either one or the other. You could change / fix the way the fuels lines were plumbed and eliminate the problem. OR. You could accept the problem and put on a vague sticker to comply with the AD. I'm not sure why the FAA (who issued the AD) didn't demand that the fuel lines be changed? Could have been pressure put on by lobbyists who were trying to save owners a few bucks?

[@eiselbay]

@@GlensHangar Awesome, thank you.

[@jimlockwood7270]

The Continental 0300 D engine can be susceptible to exhaust valves sticking also especially running 100LL it happened to me a few times in my 1966 Cessna 172 G

[@GlensHangar]

Valve sticking is a whole other can of worms. In this case the experts who looked at the engine data (Both are very Savvy and Superior in their knowledge if you catch my drift) concluded and confirmed that it was a short fuel starvation event that happened in the lines between the tanks and the fuel flow sensor - Vapour Lock. We do a have a valve problem that we've been tracking in cylinder #6; and we'll be addressing that in an upcoming episode.

[@joeyhardin1288]

Not a pilot! If you were to fly on both tanks, then why is there a switch? Smart pilot! Thank you. God Bless and stay warm.

[@a.j.alberti518]

I'm curious: is aviation fuel blended seasonally like automotive gasoline is? A few years ago I experienced symptoms very similar to what Glen describes while riding my fuel injected (no carb ice) motorcycle also on a warm April day. I limped home by stopping periodically to let everything cool down and occasionally adding a litre of fresh gas where available, after which the engine ran fine for a while. I had a long, very informative conversation with an engineer at the fuel company and concluded that the fuel in my tank was probably winter blend, which is brewed for High volatility in cold conditions. The unseasonable spring warmth (mid-20⁰s) probably caused excessive vapourization leading to vapour lock. Just wondering.

[@blakegardner2339]

How much would a quote be to re-plumb the fuel lines? Can you link the document Cessna published?

[@twest344]

What was the relative humidity on that day?

[@xx420xxyolo3]

Your left tank drains faster because thats where the fuel vent is

[@daleharsh6424]

Are we voting? I vote for vapor lock.

[@billclisham8668]

When you install either the wing extensions and/or the STOL kit do they give you the math as to your corrected stall speeds and take off and landing speeds or do you have to trail and error your way into those calculations??

[@GlensHangar]

You’re pretty much on your own to test and figure it out.

[@spurgear4]

Using the primer to get fuel to the engine may have helped troubleshooting. That being said I would be hesitant messing with an engine that's running even if its running rough.

[@GlensHangar]

That was part of my thought process - I know that messing with the primer during flight can cause issues, so why risk it. On the other hand it may have been a way to get a bit more fuel into the engine?