I'm surprised the article doesn't mention the Cessna 182, which also started production in 1956 and is still rolling out of the factory new today.
While the article extols the virtue of the 172's engine, the fact is that the vast majority of them are running very old designs with carburetors and on Avgas. Avgas still contains lead. These old engines are hugely inefficient and flown incorrectly prone to cracked cylinders. Newer models are fuel injected and there are also a few diesel conversions.
All Cessna single engine aircraft now have to undergo supplementary inspections (SIDS), at least in Australia and I think it is the same in the US. I've seen first hand the horrendous amount of corrosion which can hide in a 50 year old aeroplane and not be found until the wings are removed. These SIDS inspections have the potential to ground much of the older 152/172/182 fleet and render what was a $25,000 asset practically worthless. It will be uneconomical to repair in many cases.
The above has happened to me personally with a Cessna 182. In the end it was sold for scrap with only the engine and avionics retaining any value. I've also seen the costs of these inspections on a Cessna 210 exceed $20,000. It needed a whole new main wing spar amongst other things.
The point I am making is that these very old single engine light aircraft need very meticulous inspections now to ensure they are still safe to fly. I do believe there are probably quite a few seriously at risk aeroplanes still flying today, especially if they have been left outside in coastal areas for any length of time.
I used to own a light aeroplane maintenance business.
Agreed. I got my PP license 40 years ago on a 172, then 4 years ago went thru training again to renew but quit due to the condition of the planes (all 150's, 172's). I also quit because I realised (maybe because I'm older now), that there is no place for a part-time pilot. Too dangerous. Either you fly every day or don't fly at all because eventually something is going to happen, especially considering the planes I was flying and if you fly 1-2 times a month you are ill-equipped to handle any emergency situation.
I did a bit of training in a Cessna 152 but one day we had to take a 172 it was like going from a Yugo to a Cadillac.
In the 152 I was literally rubbing shoulders with my instructor but in the 172 we had shoulder room. The 172 has four seats and feels huge compared to the 152, well really it is huge compared to the 152.
I have my baptism flight a month ago in a 152. The instructor was worried because he couldn't fully move the wheel back because of my knees, then I tried another position and he couldn't press the pedals. It took us a while to find a position for my legs, but I didn't feel safe about this until we landed.
I am tall 1.90m (6'3"). I want to take classes further but I think I should find another plane.
Note: I used a Fiat 600 for like 6 months. I think the 152 is smaller inside.
I have 200 hours in a 150 and I'm your height. You'll get used to it. Keep in mind that the 150/2 is a better training plane than the 172. It will teach you to respect the rudder and the crosswinds, while a 172 is forgiving to the point that it may become dangerous. Also, anxiety is normal initially. I'm saying that because there's a difference of ... 1/4" between the two planes' cabin width (39 1/2 to 39 1/4).
Last time I was in the air in a private plane was a 152 a couple of months after a friend achieved his pilot's license. We're both 6'2" and around 190lbs. It took a bit of work, and we were shoulder to shoulder the entire flight, but it was workable. The cabin of the 152 is smaller than any car I've ever been inside of. There's room behind the seats for maybe two backpacks.
>I've seen first hand the horrendous amount of corrosion which can hide in a 50 year old aeroplane and not be found until the wings are removed.
If it's such a problem, how come there hasn't been a single case of a in-flight structural failure from corrosion of any strut-braced Cessna? In fact there have only been two cases of structural failure in 172s, both of which appear to have been caused by trying to do aerobatics:
It could be that the SIDS inspections are in place to prevent catastrophic structural failures.
One single edition of Flight Safety Australia in 2015 lists five reports of corrosion in Cessna singles, including specifically relating to the main wing spar.
Just to note: SIDS are not required for part 91 operations, at least in the US. If your aircraft is part of a Cessna maintenance program, then it will get lumped in, but for many older aircraft who are privately owned and flown, SIDS are recommended but not required by the FAA..at least not yet.
That has to be one of the most interesting career paths that I'm aware of. Impressed with your ability to adapt and learn outside of some narrow envelope.
I've also worked at a major dotcom, starting pre-2000 for all the fun, and in the television industry for a major UK broadcaster.
While each industry has required its own knowledge, I have more or less been applying the same set of skills. For example, now in the pharma engineering R&D role, I'm just a project manager rather than a scientist. I read a handful of in-depth papers in my specific area (Optical Coherence Tomography) and by then I could at least understand the technology. I also had just moved to a new country, needed a job and they needed someone with good English and reasonable management skills.
The horses and data science interests are linked and the direction where I want things to seriously go next. I'm learning the trade and just starting out now.
Or, you could look at my career path and deduce that I just get bored easily....
I've never really thought about it as inspiring, because it's just been "life." I try to do things I'm interested in and then when circumstances change, I look for something else.
I have a friend who was a tour guide and fitness trainer for many years. He's climbed Kilimanjaro something like 12 times. Now, in his early 40s, he is well on the way to obtaining his commercial pilot's licence. It's something he's wanted to do since a teenager and has saved towards that target for a long time. To me, that kind of dedication is inspiring.
This would now probably get into the big debate around running these engines rich of peak or lean of peak.
Generally, speaking engines of this type are manually leaned - full rich for take off, climb and landing, then leaned for fuel conservation in cruise. The debate is around whether it is better for the engine to be run slightly richer or slightly leaner over an extended period of time. Slightly lean of peak is probably better.
However, if leaned too much there is the risk of one or more cylinders overheating. Exhaust Gas Temperature (EGT) guages should be used to monitor this. Many older Cessna 172/182s wouldn't be fitted with EGTs. They certainly weren't factory standard in the 50s, 60s and 70s.
All this leaning of mixture is done manually, by turning a knob screw in the cockpit.
Another risk is shock cooling. This isn't really an issue with Cessna singles, but can be a real problem with heavier twins like a Piper Chieftain (PA31-350). They easentially run two bigger versions of a very similar engine.
When lean of peak, leaner is cooler, so the overheating risk you're describing is generally from cylinders operated "not lean enough" if the intent was to operate lean of peak.
But, in general, leaner is hotter, not cooler. At a ROP setting, the extra fuel that is not burned lands on many of the top end components including the exhaust valve. As it evaporates off the surface or out of the fuel/air charge, it cools the component or charge.
Also, peak cylinder pressures are higher when run RoP.
or the CHT line on the graph in Lycoming's (in)famous "Experts are Everywhere" document: http://users.kymp.net/kotkanik/documents/SSP700A.pdf (note that in the Lycoming document, leaner mixtures are on the left and in the APS red box graph, leaner mixtures are on the right; Lycoming graphs BSFC and APS graphs 1/BSFC)
> But, in general, leaner is hotter, not cooler.
That is not borne out by the data shown in graphical form in the links above (which agree with each other and match my experience operating big-bore Continental engines).
Only while richer than 25 rich of peak EGT is your statement correct. Lean of peak, leaner is in fact cooler, which was my original claim.
> Also, peak cylinder pressures are higher when run RoP.
From a cylinder longevity standpoint, this is a bad thing, of course. It's particularly a bad thing when cylinders are run very hot (over say 425F) because aluminum loses a significant percentage of its strength in that temperature regime: https://www.nap.edu/openbook/NX006900/xhtml/images/p20003245...
Also keep in mind that these are air-cooled engines. Due to the configuration, it may very well be the case that one or both rear cylinders are not receiving the same cooling effect as the front two. Therefore, even if you're running lean of peak, it's very, very important not to overdo it
On a Cessna 182 I used to run, I could lean it to 50-52 litres per hour, using a digital fuel flow gauge (not standard factory equipment). If I leaned to 48 litres per hour, the EGT gauges clearly showed a rise in temperature for certain cylinders.
If I was leaning without using these gauges for assistance, it would be very easy to make a mistake and overdo it, or not lean enough and waste fuel/money.
Yes. Good old fashioned corporate snark. Even though I disagree with Lycoming's estimation of how difficult it is to operate lean of peak and agree with the APS/GAMI "experts", I do appreciate that Lycoming came out swinging and published the snark.
I would recommend an all-cylinder CHT and EGT graphic engine monitor (ideally with data recording, as that makes some aspects of engine management easier).
Keep the CHTs under 380F in cruise and under 400F in climb (380F is better, but not all planes can do that at heavier weights).
Shouldn't the leaded fuel make the engine less prone to detonation and cylinder cracking? Also how do you tune carburetors on an airplane? Do you target the cruising altitude of the aircraft or above that altitude maybe?
Yes, the lead raises the effective octane, preventing detonation. The other tool for preventing detonation is running extremely rich fuel/air ratios, the typical setup for the airplane at full takeoff power.
You target an appropriately rich mixture at sea level when tuning the carb or adjusting fuel flow for injected engines. The pilot manually leans the mixture as the aircraft climbs to maintain a reasonable fuel/air ratio.
Owners sometimes call that mixture lever the money lever because it governs fuel flow, aka "dollars spent per minute".
Hjelmco is certainly fighting the good fight in that regard.
Which brings up the point of the availability of Avgas worldwide.
I had an aeroplane ferried from the UK to Australia, via the middle east and asia. Avgas, with engines only certified to use the leaded variety, was extremely hard to find and extremely expensive through much of the region. I have a photo of the aircraft being refuelled in India via hand held funnel and two gallon cans.
This also means that many of the NGO and small relief aircraft which used to be active in those areas are no more.
Still plenty of JetA1 available, but one needs a totally different engine for that.....
Last time I looked, few years ago it seemed the long term solution was to switch to diesel. Diesel has some advantages, higher efficiency means lower fuel consumption, energy per gallon is higher, but lower per pound. And also diesel is safer to handle.
Probably modern materials allow for reliable diesel aircraft engines that are lower cost over the life of the aircraft. But difficult though since the pace of development in the light aircraft industry is very slow and there is little money in it.
I wonder why there's no effort to make affordable turboprop engines in the power range required for typical GA usage. Sure, small turbines take an efficiency hit (boundary layer friction and whatnot), but still? And what makes them so expensive compared to piston engines?
But yeah, maybe small diesel engines are a better approach, shrug... And some of the designs look neat, e.g. opposed piston two-stroke like ye olde Junkers engines.
There's also efforts to create and certify an unleaded replacement for 100LL. Probably won't solve the price and availability issues with avgas, but at least it doesn't contain lead (which in addition to the environmental issues is a PITA for refineries ) and I guess it's a hedge against that last TEL-producing factory on the planet going bankrupt and grounding the fleet..
Hybrid Electric aircraft are kinda interesting when you start running the numbers.
The weight of the batteries of course reduces the amount of fuel the aircraft can carry. However increased efficiency reduces the amount of fuel you need to carry. There are a bunch of other advantages which would improve safety.
In particular better throttle response. A problem with turbine engines is when an aircraft is hit by wind shear during landing you need more power right now, and turbines have lag. And also when you shutdown an engine in a multi-engine aircraft you have a serious thrust imbalance. Hybrid electric would allow power to be routed evenly to each fan
as needed.
Traditionally you deal with the lag with variable pitch propellers. But with electric motors you can have a lot of immediate / momentary torque and power and instead vary the propeller speed.
I think what is aimed at with electrics is you get a lot simpler aircraft with far lower operating costs and higher reliability and availability.
No engine maintenance, no variable pitch propeller, no fuel systems (you do have batteries but they should be self contained man changeable systems). No huge checklists with warmup etc procedures on the ground.
It's worth it to just have 30-60 minutes of flight time, because you still get to train takeoffs and landings.
Maybe the instructor and student can first swap the new battery with 5x20 kg units or so, take off, do a few touch and go:s, land, then let the next guys do the same.
I think most everyone that tried introducing diesel aero engines in the early 2000's went bankrupt. Which actually isn't the end of things as long as the business is sound.
The QUEST Kodiak is filling in for many of the larger NGOs. I believe it was designed for that express purpose (taking over where the small avgas powered planes could no longer operate due to the price or availability of avgas).
Unfortunately Turboprops come with a whole new set of maintenance requirements but otherwise it's an excellent aircraft and working out quite well.
I think the Quest Kodiak is a great aeroplane, and very comparable to the Cessna 208. Both have many advantages over the Cessna 206s and 210s which were fulfilling these types of roles over the previous 40 years.
The biggest issues with both of these is the cost to buy and also the cost to maintain. Both are well in excess of the older Cessnas.
Not sure which comment you're replying to, but if it's my original post about hidden corrosion, then yes it will apply to all older light aviation types.
However, some are potentially more vulnerable than others. A high wing Cessna 172, parked uncovered outside in a coastal area is going to be much worse in many aspects than a low wing Piper Archer, hangared somewhere inland.
Here's an FAQ from the Australian regulator. It states that they are in discussion with Beechcraft and Piper regarding SIDS:
While the article extols the virtue of the 172's engine, the fact is that the vast majority of them are running very old designs with carburetors and on Avgas. Avgas still contains lead. These old engines are hugely inefficient and flown incorrectly prone to cracked cylinders. Newer models are fuel injected and there are also a few diesel conversions.
All Cessna single engine aircraft now have to undergo supplementary inspections (SIDS), at least in Australia and I think it is the same in the US. I've seen first hand the horrendous amount of corrosion which can hide in a 50 year old aeroplane and not be found until the wings are removed. These SIDS inspections have the potential to ground much of the older 152/172/182 fleet and render what was a $25,000 asset practically worthless. It will be uneconomical to repair in many cases.
The above has happened to me personally with a Cessna 182. In the end it was sold for scrap with only the engine and avionics retaining any value. I've also seen the costs of these inspections on a Cessna 210 exceed $20,000. It needed a whole new main wing spar amongst other things.
The point I am making is that these very old single engine light aircraft need very meticulous inspections now to ensure they are still safe to fly. I do believe there are probably quite a few seriously at risk aeroplanes still flying today, especially if they have been left outside in coastal areas for any length of time.
I used to own a light aeroplane maintenance business.