by Pete Schoeninger
Copyright 2021. All rights reserved!
Published in Midwest Flyer Magazine June/July 2021
Online Issue
Q: I have heard there has been a big jump in values of some Cessna 172 Skyhawks. Can you verify?
A: You are correct. Values have risen mostly among those 172s manufactured in the last 20 years. The 2021 spring edition of Aircraft Bluebook shows increases. The 2005 models have jumped a whopping $30,000, and 2010 models have jumped about $15,000. The middle aged Skyhawks (1975 – 1985) have seen a rise in value of about $5,000, but the really old ones with the 145 hp engine (1967 and earlier) have not gained in value. Since Cessna resumed single-engine piston production in 1997, the C172 has been their primary trainer. Therefore, a good percentage of the new C172s are delivered to flight schools around the world, whereas the C182 and C206 are more likely sold to individuals.
Q: What are the single-engine aircraft sales between the three largest manufacturers: Cessna, Piper and Cirrus?
A: The General Aviation Manufacturers Association (GAMA, https://gama.aero/) has posted aircraft shipment information for year 2020: https://gama.aero/wp-content/uploads/2020ShipmentReport-03162021.pdf. Rather than risk confusing single-engine piston, turboprop and jet aircraft sales, please look and compare for yourself.
Q: Textron Beechcraft is advertising their Bonanza as having the longest continuous production in the world of 75 years. Is that true? What about Cessna 170/172s, and Piper Cubs?
A: Bonanza ads claiming the longest continuous production are correct. Bonanzas were introduced in 1947, with a price of about $11,000. The Cessna 170 came out in 1948 and became the C172 in 1956 and is in production right now. But Cessna shut down their piston line from about 1986 – 1997. The Piper Cub was manufactured between 1938-47, and the Piper Super Cub was manufactured between 1949-83 and again between 1988-94. (Cub clones are now made by a couple of different manufacturers, but not by Piper.)
Q: Carb heat question please. I rode with a real high-time pilot recently in his Cessna 140. We did the usual runup for mags, but when he pulled the carb heat knob, he kept it on for about 20 seconds. He then pointed out to me that we picked up about 25 RPM over initial reading. He said, we picked up some carb ice, so we’ll give it one more shot of carb heat just before takeoff to make sure it’s clear. Sure enough, just before takeoff he checked carb heat again, and the tach again showed a reduction in RPMs, but not as much as first indicated. Then, to my astonishment, he started his takeoff roll with full carb heat on. As he neared the application of full power, he pushed carb heat in with his right thumb as his right palm worked the throttle. Wasn’t this overkill?
A: No, not at all. In many airplanes, the carb heat knob can be operated simultaneously with throttle movement.
Remember, this is about carbuetor ice: If you suspect carb ice put on carb heat and LEAVE IT ON until engine power resumes. As ice melts and goes through the engine, the engine may run rough.
I can recommend the following internet websites for additional information: 1) “Carb Ice, it can happen quickly.” In this video, a 150 hp engine begins to lose power about 2 minutes after takeoff into clear air. Listen carefully and you can hear the engine lose a little power, and then stumble when carb heat is applied and then it resumes full power. 2) “Combatting Carb Ice – AOPA.” This is a great instructional website, and 3) “Carb Ice Probability Chart-AOPA.” Note, carb ice is possible over a wide range of temperatures from perhaps 20 degrees Fahrenheit, up through about 90 degrees Fahrenheit.
Q: Last winter, I accompanied a friend in his Cessna 172 to land on a frozen lake. We flew over the lake and he commented that the landing area was about 2500 feet long. I asked him how he knew this, and he said it was just a guess. Is there a better way to judge distances on a prospective landing site, especially one on a frozen lake?
A: Yes! Multiply your groundspeed in mph times 1.5 to get approximate distance in hundreds of feet. A 70-mph groundspeed works out to be about 100 feet traveled per second. So, if you flew over a lake – or a big field – at 80 mph into a 10-mph headwind, your groundspeed is about 70 mph, and if it takes you 25 seconds to cover the length of that field or lake, the field is roughly 2500 feet long. If you are in a faster airplane, you can use a groundspeed of 100 mph = 150 feet traveled per second. (Purists and math majors will correct me to say the constant should really be 1.47, but for me, 1.5 is close enough.)
Q: I have been tasked with selling my uncle’s Cessna 185. I think I should hire a salesman or sales company to handle the sale, as I have no experience in selling airplanes, and I know very little about Cessna 185s, their quirks, values, etc. With that in mind, I contacted two airplane salesmen. The first person was a well-regarded man who is known for giving instruction in, and selling, Cessna 180 and 185 airplanes. He looked at our airplane and examined all maintenance records. He estimated he could sell the airplane for $100 – $110K and wanted a 120-day listing sale contract with 6% commission to him upon sale closing. An FBO about 60 miles away has just hired a rookie airplane salesman and I asked him to come look at the airplane. He looked it over and admitted he did not know much about C185s, but said based on bluebooks and internet ads, he could sell it for $135K or so, and he wanted a year’s listing. Who would you list the aircraft with?
A: The world’s best airplane appraiser is the guy who is active in the market of your make/model similar to yours, regardless of bluebooks, other people’s ads, etc. You’ll be tempted to go with the new salesman and his higher price estimate, but I would go with the veteran. The experienced man knows the market, can fly your airplane, knows where to advertise, and probably already has a list of potential C185 buyers. Besides, a 4-month listing contract beats a 12-month listing contract and demonstrates that the salesman has more confidence and will be able to sell your airplane faster.
Q: I just read that mechanical tachometers (like in my 1984 Skyhawk) can have significant errors, perhaps as much as 125 RPM. Can you verify this?
A: Yes, some mechanical tachometers can be off as much as 5%. Your mechanic probably has a tachometer checker and could check your readings in short order. I’ve also seen aircraft owners gripe about a lack of performance (lower cruise speeds and sometimes a reduced rate of climb) from their airplane with fixed pitch props, because they were running the engine 100 RPM less than they thought.
Q: Follow up question regarding my 1984 Skyhawk. I did check the tachometer, and it is within 20 RPMs of true. But my airspeed is about 10-15 mph below what the Pilot’s Operating Handbook suggests I should be getting. I have flown my airplane in loose formation with a friend with a Mooney and our indicated airspeeds are very close, so I think the airspeed indicator is not at fault. Ideas?
A: With an accurate reading tachometer, you can now assume when you are running at the cruising RPM you desire, but you are still 10-15 mph slower than anticipated, I suspect your prop is the villain, in one of two ways: 1) Maybe your prop is old and has been filed on many times and has lost some of its aerodynamic ability to pull as much thrust as it used to. It probably needs to be reconditioned or overhauled or replaced if it is too far gone. 2) Perhaps your prop has been re-pitched to a different pitch setting, rather than the 57-inch pitch your airplane’s prop should have. It sure wouldn’t hurt to send your prop off to a prop shop to be checked over.
Q: My friend has a 1939 Piper J-3 Cub (legally a J-3L-65), and I have a 1946 J-3 Cub (legally a J-3C-65.) Both have 65 hp Continental engines. I looked at his limitation sheet and was astonished to see that his gross weight is only 1100 lbs., whereas mine is 1220 lbs., even though the empty weight of both aircraft is around 725 lbs. Can you clarify?
A: Your friend’s airplane was manufactured with a 65 hp Lycoming engine, but somewhere over its very long life, the 65 hp Lycoming was replaced with a 65 hp Continental. But the airplane is still a J-3L-65, with all limitations of gross weight, CG, airspeeds, etc. Most of the Cubs made before WWII had a gross weight of only 1100 lbs., but with some improvements, that could be raised to 1170 lbs. I once owned a Piper J-3C-65. It had a 75 hp Continental engine, but it was still a J-3-C65.
Q: I started giving dual instruction to a private pilot in preparation for his Commercial Pilot Certificate. (He has a Cherokee and he only flies in very good VFR weather, without problems so far.) Progress has been very slow, and I suggested he try another flight instructor, which he did. Unfortunately, his second instructor is not having any more luck than I did. Have you ever gotten to the point of suggesting that a student not continue their quest for a higher certificate or rating?
A: Yes, but first I want to comment on the student. You said he owns a Cherokee and has flown for a while as a private pilot, but he is not gaining Commercial Pilot competency. I think you should tell him that while his skills may be safe for simple flights in a simple airplane in good weather like his Cherokee, he is going to spend thousands of dollars in training and may never reach Commercial Pilot competency. You also could suggest that his time and resources might be better spent trying to be the safest and best Private Pilot he can be. Nothing wrong with that.
EDITOR’S NOTE: Pete Schoeninger is a 40-year general aviation veteran, starting out as a line technician as a teenager, advancing through the ranks to become the co-owner and manager of a fixed base operation, and manager of an airport in a major metropolitan community. He welcomes questions and comments via email at PeterSchoeningerLLC@gmail.com.
DISCLAIMER: The information contained in this column is the expressed opinion of the author only, and readers are advised to seek the advice of others, and refer to aircraft owner manuals, manufacturer recommendations, the Federal Aviation Regulations, FAA Aeronautical Information Manual and instructional materials for guidance on aeronautical matters.
