by Richard Morey
© Copyright 2023. All rights reserved!
Published in Midwest Flyer Magazine June/July 2023 Digital Issue
Flows, Checklists, and Carburetor Ice. Thankfully emergencies rarely happen. When they do, quite often the pilot is taken by surprise and may be unprepared to immediately deal with the situation. General aviation pilots seldom spend time on emergency drills. This article will give you suggestions to make emergency (and other) checklists more user friendly, to incorporate flow into your checklists, and will make suggestions as to how to practice emergency procedures, as well as ways in which emergency procedure practice can be incorporated into every flight. Let us begin.
In an emergency, we may or may not have time to go to a checklist. As discussed in the “Startle Effect” article (June/July 2022, Midwest Flyer Magazine, https://midwestflyer.com/?s=Startle+Effect) and seminars, acknowledging that something may go wrong and planning for that unlikely eventuality will reduce reaction time and make a good outcome more likely. Knowing that something can happen is not enough. To become good at anything, we need to practice and repeat. We also must make sure that what we practice is correct. What we do and practice must make sense. For that to happen, we need to understand what the actions call for, and actually do. The order in which these actions are taken should allow the pilot to easily remember and execute the steps.
pilot’s operating handbook
A good place to start your practice is with the aircraft’s manual or pilot’s operating handbook (POH), and the emergency checklist. This will ensure that the procedures practiced are correct as far as the manufacturer recommends. With older aircraft, the manuals were often quite brief and not terribly detailed. If that is the case, then exploring owner groups and online resources may be your best option. Owners of classic aircraft may have to do even more research and, in some cases, simply develop checklists based on best practices.
Familiarize yourself with the checklists. This can be as simple as reading over the lists. I recommend doing this in the aircraft sitting in the seat you normally occupy when flying. Read the checklist, stopping to touch the controls mentioned at each item. Make sure the order and what you are accomplishing at each point makes sense.
Do the checklist items make sense? Does the order “flow” well for you? If not, take the time now to think about what is being accomplished at each step.
Does the order make any difference?
For example, let’s examine the Cessna 152 Pilot’s Operating Handbook checklist for engine failure during flight with the option for restart. We will go over the action and the reason for that action:
1. Airspeed – 60 KIAS
2. Carburetor Heat – On
3. Primer – In and Locked
4. Mixture – Rich
5. Ignition Switch – Both (or START if propeller is stopped).
Notice that the first two items are in bold print. Cessna uses bold print to indicate items that should be memorized:
Item 1, Airspeed – 60 KIAS is best glide, Vg. Every pilot should have memorized the best glide speed for the aircraft they fly. Going to best glide will maximize the aircraft’s time in the air, normally a good thing during an emergency.
Item 2, Carburetor Heat – On. One of the most common causes of engine roughness or failure on carbureted engines is carburetor ice. Applying carburetor heat could melt the ice that may have formed on the butterfly valve in the carburetor and solve the issue. More on carburetor heat later.
Item 3, Primer – In and Locked. If the primer is unlocked and out even slightly, the engine could be sucking additional and unneeded fuel into the engine’s induction system through the primer. This could cause the mixture to be far richer than it should be. That is, more fuel than the air taken in is able to burn efficiently. Making sure the primer is in and locked will prevent excessively rich mixture due to syphoning fuel through the primer.
Item 4, Mixture – Rich. Just the opposite of the primer being locked. If for some reason the aircraft is running lean, as in there is not enough fuel for the air being taken in for it to burn efficiently, then the engine could run rough, lose power, or stop. Enrichening the mixture solves that potential issue.
Item 5, Ignition Switch – Both or start if the engine has stopped. If for some reason the ignition switch has been turned off, turning the ignition back on while the propeller is wind milling should send spark to the engine combustion chambers via the spark plugs. If the engine is getting spark and fuel and air in the proper ratio, then the engine should restart. If the propeller has stopped turning, then engaging the starter should start the engine unless there are other issues. Once you understand the reasons for doing the checklist items, the process makes more sense.
How does the checklist “flow” in your mind? If the order seems awkward, then how can you make the checklist work better for you? The memorized items – best glide, and carburetor heat – need to stay in the order Cessna has on the checklist. Cessna has decided that these two items require “immediate action” and as such, need to stay in the specified order. For the other items, would it really matter if enrichening the mixture comes before checking the primer? For those not familiar with Cessna 152s, the primer is on the far left side of the lower panel, next to the ignition switch and the carb heat, and throttle and mixture are located in the center. After establishing airspeed, the right to left flow of carburetor heat, mixture, then primer and ignition may make the process easier to remember. As you can see from the picture of a Cessna 152 panel, the carburetor heat, mixture, primer then ignition order keeps the pilot’s attention in the same sector, rather than having to jump back and forth.
This is a simple example of making an emergency checklist make sense and flow. If you go through this process with all the emergency checklists, and normal ones as well, then you will be much more likely to remember the steps when an emergency occurs.
This process works for all makes of aircraft. There is nothing illegal in creating your own checklist, starting with the manufacturer’s checklist and change out the order of the non-critical checklist items. It is easy to create a Word document and save it, so as to be able to print out additional copies or modify the document if needed. Laminate the printout and keep a copy in your aircraft for easy reference. Again, be sure to include all items on the manufacturer’s checklist.
The reality is that engines seldom suddenly quit unless they run out of fuel. An engine in trouble will almost always give indications, such as rough running or loss of power. What you often read or hear when discussing engine emergencies is the following:
“Through proper scan and being aware of what could go wrong, the alert pilot should be able to determine something is wrong long before the engine quits.” Not terribly helpful in and of itself, is it? Unfortunately, there is not a “rough running engine” checklist, at least not in the Cessna manuals.
As an exercise, we are going to create a rough running engine/loss of power emergency checklist. To do so we must understand what could cause an engine to lose power and/or run rough. We will use the checklist for a carbureted Cessna for our example.
One of the most likely reasons for a carbureted engine to lose power is the formation of carburetor ice. Loss of power will occur well before carburetor ice causes the engine to run rough. What happens when an aircraft is trimmed for level flight and power is reduced? If your answer is the aircraft will descend, you are correct. If the aircraft is on autopilot, then you might notice the autopilot calling for nose up trim, or the autopilot trim adding nose up trim, depending on the type of autopilot. In this case, loss of power and nose up trim results in a slower airspeed.
For our rough running engine checklist, Item #1 is loss of altitude (or loss of airspeed, if on autopilot) not associated with downdrafts, apply carburetor heat. If there is carburetor ice, adding carburetor heat will result in a rough running engine. As the ice melts and is passed through the engine, the engine will then smooth out and an increase in power will be noted. Putting the carburetor heat control to the off position once the engine is running smoothly, should return the engine power to the level set initially prior to carburetor ice forming. The longer the carburetor ice is allowed to form, the greater the loss of power. Eventually, the engine will start running rough. If enough ice is allowed to form, the engine may initially quit when carburetor heat is applied. Keep the carburetor heat in the “on” position and the engine will start up again once the water passes through the engine.
Checklist Item #2: Rough running engine or power loss. Check fuel on and on both. If on both, switch to a single tank. If still rough, try opposite tank. It is possible, however unlikely, for the fuel valve to be accidently bumped into the off position. The likelihood of this happening is greater if you have a creative flight instructor onboard. Still, checking the fuel selector is a good idea. Changing tanks may smooth out a rough running engine if there is water contamination in one of the tanks. First, check one side, then if the engine does not smooth out, switch to the other.
Checklist Item #3: Check mixture. If lean, enrichen. If rich, lean. Flying with ether a too rich or too lean mixture may result in a rough running engine or loss of power.
Checklist Item #4: Check throttle. The throttle may have slipped back, resulting in power loss. With a rough running engine, changing the power setting could improve the roughness.
Checklist Item #5: Do a magneto check. It is very possible that one magneto has stripped its gears and is firing out of sequence, which causes the engine to run rough or miss. If the engine runs rough on both magnetos, really rough on one, and smooths out on the other, then fly it on the smooth magneto and land as soon as practical. If that does not work, return the ignition switch to both.
Checklist Item #6: Check the primer. If the primer is in and locked, try giving the engine a shot of prime. If this results in more power, continue to prime the engine as needed to make a safe landing. Back before paper engine air filters were required to be replaced every 500 hours, we had a customer’s air filter come apart during flight. This resulted in part of the filter being ingested into the carburetor. The piece of filter ingested blocked air flow causing the loss of most of the power of the engine. This occurred only a few miles from the airport. By using the primer, the pilot in essence became a crude, manually operated fuel injection system. Pumping the primer gave the aircraft enough power to make it back to the airport.
This list is in more detail than the manufacturer’s. It is based on the aircraft’s manual but goes into more detail. As shown, it does not flow though. How do you think we could improve the order to make the list flow better?
Visualize an inverted L with the bottom of the L being the fuel selector which is located on the floor or at the bottom of the center pedestal.
1. Check Fuel Selector On (go back to switching tanks at the end of the checklist).
2. Mixture rich if leaned, or lean if rich.
3. Throttle Checked and Varied.
4. Carburetor Heat On
5. Magneto Check
6. Primer Check
The inverted L check can be accomplished almost as fast as it can be read. If any action results in the engine running smoother or power being restored, stop the checklist, and continue the flight. Use your judgment in deciding whether to continue the flight. Flying on one working magneto is not recommended, but one magneto will most likely get you to the nearest suitable airport.
Practicing emergency procedures can easily be incorporated into each flight. Make a pre-takeoff emergency briefing prior to each flight.
Pattern work? Try taking the power off opposite your landing spot with the goal of making the runway safely without adding power. A brilliant practice that was mentioned at a recent FAA safety seminar is to set your watch or phone alarm to go off sometime during your flight. When the alarm goes off, assume an emergency has occurred. Go through the appropriate flow, memory items, identify an emergency landing spot and go through the associated checklists.
Emergencies do happen. When they do, there is often little time to go through a checklist. Knowing this, it is important not only to have the immediate action items memorized, but to have the checklist in a format that makes it easier to accomplish and remember during a stressful event. The order of a checklist may be adjusted to allow for a better flow, as long as the immediate action items stay in the order specified by the manufacturer. Practice emergencies! You will not get better without practice. Be safe!
EDITOR’S NOTE: Richard Morey was born into an aviation family. He is the third generation to operate the family FBO and flight school, Morey Airplane Company at Middleton Municipal Airport – Morey Field (C29). Among Richard’s diverse roles include charter pilot, flight instructor, and airport manager. He holds an ATP, CFII, MEII, and is an Airframe and Powerplant Mechanic (A&P) with Inspection Authorization (IA). Richard has been an active flight instructor since 1991 with over 15,000 hours instructing, and more than 20,000 hours total time. Of his many roles, flight instruction is by far his favorite! Comments are welcomed via email at Rich@moreyairport.com or by telephone at 608-836-1711. (www.MoreyAirport.com).
DISCLAIMER: The information contained in this column is the expressed opinion of the author only. Readers are advised to seek the advice of their personal flight instructor, aircraft technician, and others, and refer to the Federal Aviation Regulations, FAA Aeronautical Information Manual, and instructional materials concerning any procedures discussed herein.
