Topics this week include: >> Shake it up >> Don’t assume >> Getting crossways
FLYING LESSONS uses recent mishap reports to consider what might have contributed to accidents, so you can make better decisions if you face similar circumstances. In most cases design characteristics of a specific airplane have little direct bearing on the possible causes of aircraft accidents—but knowing how your airplane’s systems respond can make the difference in your success as the scenario unfolds. So apply these FLYING LESSONS to the specific airplane you fly. Verify all technical information before applying it to your aircraft or operation, with manufacturers’ data and recommendations taking precedence. You are pilot in command and are ultimately responsible for the decisions you make.
FLYING LESSONS is an independent product of MASTERY FLIGHT TRAINING, INC.
Pursue Mastery of Flight®
This week’s LESSONS
You’re flying smoothly, when suddenly the airplane is vibrating badly. What do you do? What might be causing the vibration?
There’s no way to know immediately. But there’s one response that may help in a number of different scenarios: reduce power, and reduce airspeed.
The vibration likely comes from one of these causes:
- A propeller imbalance or partial prop separation
- Control surface harmonic vibration or flutter
- Partial engine failure, including cylinder head separation or fuel delivery to one but not all cylinders
- Propeller overspeed
In some cases reducing power and airspeed will stop the vibration. Control surface flutter or harmonic vibration is very sensitive to airflow, and should stop almost immediately with a change in indicated airspeed. Propeller overspeeds can usually be brought under control with a power reduction—those airplane types with a Propeller Overspeed checklist usual recommend:
- Throttle – IDLE
- Airspeed – DECREASE
A propeller imbalance resulting from asymmetric ice shedding might be fixed with a propeller rpm change, which changes the angle of attack of the prop blades and tends to break off ice that has formed.
A partial propeller separation is extremely serious because the shaking may be enough to tear the engine off its mounts. If the engine actually departs the airframe, the resulting center of gravity shift may make the airplane uncontrollable.
Control surface vibration or flutter is the result of control imbalance or exceeding design airspeeds. Flutter, especially, is extremely hazardous because it can tear a control surface from the airframe in just about the time it takes the pilot to recognize the event is taking place. Vibration or flutter can severely bend or crack nearby airframe structure; in many cases it’s enough to render the airplane forever unflyable.
Vibration from partial engine failure will not go completely away with a reduction in power, but it might become much less obvious.
Propeller overspeed (rpms well beyond the tachometer redline) may cause vibration along with a tremendous increase in noise. Left unchecked a prop overspeed can lead to hub or blade failure and a subsequent severe vibration from the imbalance. Pull the throttle and slow the plane down, and you can usually regain propeller speed control, at least temporarily.
Most single-engine airplanes with controllable props will go to overspeed when oil pressure is lost in the prop dome. In fact, prop overspeed may be your first indication of a catastrophic engine oil loss. Note the overspeed, reduce power to reduce rpm, and check the oil pressure and temperature gauges.
Most multiengine airplane propellers will automatically go to feather with oil loss. This makes prop overspeed in twins much less likely. However, some propellers have an air-charged chamber in the propeller dome opposite the oil-charged side. If the air (usually nitrogen to resist corrosion) leaks out this may make a propeller overspeed in these designs possible.
Whether nor not a power/airspeed change stops the vibration, land at the very earliest opportunity to check for damage except in the case of asymmetric ice shedding, if you can positively determine propeller the ice was the cause. Don’t assume just because you’ve stopped the vibration that the problem has gone away. You may find airframe wrinkling, propeller cracking or even major airframe cracking when you have a chance to look at inflight vibration’s aftermath.
Questions? Comments? Supportable opinions? Let us know at [email protected].
Debrief
Readers write about recent LESSONS:
Reader Keith Armes or World Transport Photography writes about my sister publication, the Beech Weekly Accident Update:
Hi. [I j]ust read your 3/17-3/25 Beech aircraft weekly update and noticed news regarding the accident of N15VM Beech Bonanza at Saluda, South Carolina. You[r] description indicated that damage was “unknown.” As an update, the damage was extensive, such that the aircraft was dismantled, put on a flatbed, and trucked to Atlanta Air Salvage in Griffin, Georgia (located next to the Griffin-Spalding Airport, 6A2). Another V-Tail lost.
Keith sent me a photo of the airplane, heavily damaged and partially dismantled, in the salvage yard.
My Beech Weekly Accident Update reports come, at least initially, from FAA and unofficial preliminary reports. Most of the time these reports state the level of damage is “unknown” or “not reported,” so that’s what I report unless there is good reason to report otherwise (such as Keith’s photograph). Sometimes I can get better information from sources such as the Flight Safety Foundation’s Aviation Safety Network (ASN) or even photos on local news websites. And the NTSB preliminary reports usually update the damage assessment, although NTSB rarely calls an airplane “destroyed” even if impact damage warrants—past Board member and FLYING LESSONS reader Bruce Landsberg told me once that NTSB doesn’t want to be the one to pass judgment that an airplane cannot be rebuilt even when that’s clearly the case.
When I get better information I update the “WAU,” as I’ve done as noted in this week’s report because of your input. Thank you, Keith.
Two readers, Clay Harden and Matt Guthmiller, wrote about the NTSB report I used last week to prompt LESSONS about crosswind landings and Airplane Flight Manual (AFM) and Pilot’s Operating Handbook (POH) Maximum Demonstrated Crosswind Components. Clay writes:
At the time the HA-420 [Honda Jet] was certified, a CROSSWIND LIMIT was required in the AFM. This is highly unusual, as you indicate. That may have changed since, but I’m not sure.
Matt adds:
Some good points. I certainly find my landings are better in a crosswind because I’m paying more attention.
In the Honda Jet it’s most certainly a limitation though. It has some unique design and handling characteristics that necessitate that, and if the demonstrated crosswind is found in flight test to be limiting, it has to be published as a limitation in section 2. Most jets also have engine limits around crosswinds too (i.e. no static takeoffs with more than X crosswind for instance, things like that).
Interesting. I checked the HA-420 Type Certificate (A00018AT) and don’t see a crosswind limit listed. It does say “The aircraft must be operated in accordance with the FAA approved Airplane Flight Manual,” so if it’s in the AFM Limitations then it indeed applies. Thank you both for your insights into this specific design.
Reader Ed Stack continues:
Another great LESSON, Tom. My feedback to all pilots would be to practice crosswind landings on a regular basis. Ideally, fly to an airport with intersecting runways so that one of them will have a crosswind component. Practice crosswind approaches up to maximum recommended limits, and until you feel proficient plan them to a go-around. Don’t forget to maintain crossing controls all the way through the landing rollout. It’s not over once you touch down.
As an airline pilot, the last item I ask for in my annual simulator training every year is a 90° crosswind from 33 gusting to 40. This is well outside the manufacturer published limit, but doing that lets me know that I can handle any wind on the line for the upcoming year. If you practice regularly, you won’t fear the wind, and you won’t botch the landing.
As long as part of your practice is to go around if you have any doubt. Thanks, Ed.
Reader Marc Delude wraps up this week’s Debrief:
The maximum demonstrated crosswind in the POH/AFM has been the source of many conversations with the conclusion just about always being aligned with the points you made. Unlike, say, Vmo or a limitation on tailwinds during jet engine start, it’s not a limitation within which the pilot is required to operate the aircraft but, rather, a data point for very strong consideration of all factors affecting the flight. I have found that using a crab technique for most of the descent to landing and then changing to a wing-low sideslip into the wind in the final few hundred feet allows me to judge whether the landing can be safely completed.
Also of note is that crosswind landings are a perishable skill and repeated practice and exposure to strong crosswinds when runways more aligned with the wind are in close proximity is essential for having the skill and confidence to complete landings in strong cross winds.
Well stated, Marc. Thank you.
More to say? Let us learn from you, at [email protected].
Share safer skies. Forward FLYING LESSONS to a friend.
Please help cover the ongoing costs of providing FLYING LESSONS through this secure PayPal donations link. Or send a check made out to Mastery Flight Training, Inc. at 247 Tiffany Street, Rose Hill, Kansas USA 67133. Thank you, generous supporters.
Thank you to our regular monthly financial contributors:
Steven Bernstein, Montclair, NJ. Robert Carhart, Jr., Odentown, MD. Greg Cohen, Gaithersburg, MD. John Collins, Martinsburg, WV. Dan Drew. Rob Finfrock, Rio Rancho, NM. Norman Gallagher. Bill Griffith, Indianapolis, IN. Steven Hefner, Corinth, MS; Ellen Herr, Ft Myers, FL. Erik Hoel, Redlands, CA. Ron Horton. David Karalunas, Anchorage, AK. Steve Kelly, Appleton, WI. Karl Kleiderer. Greg Long, Johnston, IA. Rick Lugash, Los Angeles, CA. Richard McCraw, Hinesburg, VT. David Ovad, Resiertown, MD. Steven Oxholm, Portsmouth, NH. Brian Schiff, Keller, TX. Paul Sergeant, Allen, TX. Paul Uhlig, Wichita, KS. Richard Whitney, Warrenton, VA. Jim Preston, Alexandria, VA. Johannes Ascherl, Munich, Germany. Bruce Dickerson, Asheville, NC. Edmund Braly, Norman, OK. Steven Hefner. Lorne Sheren, New Vernon, NJ. “The Proficient Pilot,” Keller, TX. Kynan Sturgiss, Hereford, TX. Bluegrass Rental Properties, LLC, London, KY. John Foster. Joseph Victor, Bellevue, WA. Chris Palmer, Irvine, CA. Barry Warner, Yakima, WA. Todd LeClair, Cadiz, KY. Jim Hopp, San Carlos, CA. Adrian Chapman, West Chester, PA. Ed Stack, Prospect Heights, IL. Robert Finley, Dubois, Wyoming. Robert Finley, John Kinyon, Lawrence Copp, V. Andrew Smith, Kevin Echols. Claude Bundrick, Shreveport, LA. John Croft, Upper Marlboro, MD.
Thank you to these 2026 donors:
Robert Sparks, Mark Sletten, Thomas Jaszewski, Douglas Olson, David Field, Michael McRobert, Wayne Colburn. Albert Chaker, Textron Aviation Employees Flying Club, Denny Southard, Henry Fiorentini, Thomas Fankhauser, Rob Humble
Pursue Mastery of Flight®
Thomas P. Turner, M.S. Aviation Safety
Flight Instructor Hall of Fame Inductee
2021 Jack Eggspuehler Service Award winner
2010 National FAA Safety Team Representative of the Year
2008 FAA Central Region CFI of the Year
FLYING LESSONS is ©2026 Mastery Flight Training, Inc. For more information see www.thomaspturner.com. For reprint permission or other questions contact [email protected].