Hi, I’m Bruce Landsberg and welcome to the Leading Edge. We’ll discuss safety-of-flight issues, procedures, techniques, and judgment. With the convective nature of Internet misinformation, and so much content that is over weight and out of balance, you need an experienced and trusted source. So, strap in and let’s go fly!

Prop Problems

September 21, 2015 by Bruce Landsberg
Inadvertent Q-Tip Prop

Inadvertent Q-Tip Prop

Propellers are unsung mechanical heroes of GA. Jets are wonderful, but for those of us who pay our own expenses chances are good that a prop is the driving force. Few such high performance items on an aircraft perform so reliably with so little attention. Even when abused they often perform beyond the call of duty—but then perhaps a Darwin Award is in the offing.

A young CFI was asked to drop the owner of a fixed-gear Cherokee off at his destination and fly back solo. On preflight he noted that the owner had invested in a Q-tip prop, the kind that is bent back at the tip about an inch to improve performance and reduce noise.

Shortly after takeoff it became apparent that this particular engine, prop, and airframe arrangement was not quite optimal. The best climb they could get was about 100 feet per minute despite being far from the aircraft service ceiling. Being on an IFR flight plan, ATC was not happy.

Upon landing, the CFI asked the owner about lack of performance—this was the slowest climbing airplane he’d ever seen. Then came the admission about a really hard landing—somewhat on the nose wheel—but not to worry, everything seemed to be in order. The CFI flew the aircraft back to the departure point under VFR. Seems the Q-tip “configuration” came about as a result of the nose-first landing. How the gear didn’t collapse or the firewall avoided buckling is anyone’s guess. Later, the CFI admitted that it probably wasn’t the smartest thing he’d ever done.

Another instructor, whom I know really well, was asked to give an instrument proficiency check to a Beech Sierra owner. The CFI, having not flown the aircraft before, gave it a very thorough preflight and noted a significant ding in the prop about four inches from the tip. It had been dressed out and was smooth in all facets. The owner said the aircraft had been through several annual inspections and that there had been no problem whatsoever.

The IPC went smoothly, but on the owner’s very next flight with his wife aboard, the prop tip separated and they had to set down in a corn field. The aircraft was written off. Fortunately, there were only minor injuries. It could have been a lot worse. To this day, I should have listened to that inner voice that said, “Wait a minute…this doesn’t feel right!,” and rejected the aircraft. Whether it would have made a difference to the owner is open for discussion.

When a prop tip separates the rotational forces instantly become more unbalanced than the Federal budget. We’re talking literally tons of force. If the engine is not shut down immediately there is a very good chance that it will break the mounts and quite possibly depart the aircraft.”Losing an engine” takes on a whole new meaning. Devoid of engine and any sort of balance—well, you get the idea.

When pilots forget to put the gear down it sometimes results in a prop modification as shown on this Aerostar. The mishap was caught on video as the pilot landed gear up, but he aborted the landing and returned to home base. Rumor has it the aircraft was put up for sale immediately with the caveat of “some prop damage.” Q-tipping your own props is not an approved owner-performed maintenance procedure for obvious reasons.

At the risk of stating the obvious, any prop strike calls for a mandatory engine teardown and complete inspection. Crankshafts may suffer hidden damage and are often replaced rather than chance a catastrophic failure that may occur immediately or not for years. The risk just isn’t worth it.

To avoid the dings that caught my Sierra pilot, avoid run-ups anywhere there’s gravel or even sand. If the airport doesn’t do a good job of dealing with FOD ( foreign object debris) you may get FOD—Foreign Object Damage.

Rolling takeoffs aren’t a bad idea IF runway length allows it and there’s enough fuel on board to avoid unporting a tank. It’s less likely to abrade the prop tips. There’s always a trade off.

Periodic prop overhaul and balancing are more than just good ideas and they deserve just a little more respect. The Air Safety Institute has a great free online course that covers both engines and props.

Bruce Landsberg,
Senior Safety Advisor, Air Safety Institute

ASI Online Safety Courses  |  ASI Safety Quiz

In the Dark of the Night

September 8, 2015 by Bruce Landsberg

HNL SectionalHumans have been flying into mountains since the dawn of flight. It’s what some of us do. We know the mountains are there but perhaps it’s another version of “see and avoid.” It only works when the target is seen—not so well if it isn’t.

Then comes Risk Managementthe watchword in aviation for decades. No matter how we rationalize it, there is some risk in leaving the planet. The management part comes in determining how much you’re willing to take on—especially when carrying passengers and should that make any difference?

A preliminary report from the NTSB’s August 2015 files serves as a case study on what might be a reasonable risk or what might be a bridge too far. You be the judge. All the usual caveats about preliminary reports apply. However the general circumstances, if not probable cause, seem to be well established.

HNL EarthAccording to the NTSB, a Cessna 172 collided with mountainous terrain (a vertical rock face) at an elevation of 5,046 feet. The VFR flight departed Helena, Montana, at about 2215 Mountain Daylight Time and crashed about 15 minutes later. The destination was White Sulfur Springs, which was about 20 minutes beyond the crash site if a direct course were flown.

A few items for your consideration:

  • As noted on the chart, there are some 8- to 9,000-foot mountains on the 45 mile route with smaller ridges in between. The approximate accident location was 18 miles east of Helena, so apparently the crash occurred before getting to the higher mountains.
  • The 59 year old private pilot had obtained his certificate less than a year before the accident but had logged an impressive 280 hours, almost all of which were in the accident aircraft. He had 3.8 hours of night flight, but only .8 in the prior eight months. No indication if he was current to carry passengers at night although really not relevant here since this would be hard to describe as a landing – the flight never got that far.
  • The engine appeared to be producing power and the flaps were set at 10 degrees – an unusual configuration for cruise.
  • The weather at Helena included winds from 250 degrees at 5 knots, visibility 5 statute miles, haze, an overcast cloud layer at 4,800 feet, temperature 22 degrees C, and dew point 4 degrees C. Density altitude was calculated to be about 7,200 feet.
  • Aircraft instrumentation and portable device information was not reported in the preliminary investigation, so there is no data regarding synthetic vision or other terrain avoidance equipment.
  • Dark night conditions prevailed.
  • A family member was on board.

The late great comedian George Carlin in the weatherman sketch noted that tonight’s forecast is for dark—a profound observation.

If you’ve flown a dark night VFR flight, it’s best done mostly on instruments regardless of weather reports. There is a distinction between a dark night, which some would call redundancy, and a not-so-dark night. VFR with a full moon, especially with many ground lights near a large city, can be done with a reasonable degree of safety. Over water and in unpopulated terrain it’s an instrument game. A complete engine stoppage in any kind of dark would be problematic but we rationalize that those are rare.

Mountains compound things tremendously even if the pilot doesn’t suffer spatial disorientation. You can be cruising along minding your own business when the earth suddenly rises up to inflict a fatal sudden stop. Many old timers will not fly in the mountains at night regardless of how good the weather is and some avoid night flight completely.

In the flatlands it’s the dark departures and arrivals that cause problems assuming a reasonable enroute altitude. That can be managed by not flying into short fields unless good local knowledge keeps you out of the rough. Electronic navigation to supplement poor human night vision is invaluable while enroute and at the destination.

So based on what is known at this point, was this a prudent flight, in your view? Should a passenger be factored into the equation in determining risk?

Learn more

Read, Safety Pilot: Landmark Accidents “Comfortable and complacent: A dark night, high terrain, and a climbing skyline” and take the Air Safety Institute’s “Mountain Flying” online course.

Bruce Landsberg,
Senior Safety Advisor, Air Safety Institute

ASI Online Safety Courses  |  ASI Safety Quiz

The not-so-easy takeoff

August 26, 2015 by Bruce Landsberg

Takeoff croppedOh to slip the surly bounds and soar skyward. Takeoffs are easy compared to landings—right? Just add power, a little right rudder, and wait for the magic to happen. What could possibly go wrong?

A casual peruse of this July’s preliminary accident reports shows that bad things happen on takeoff, although percentage-wise it’s a small number. A partial listing: A Comanche lost power shortly after takeoff—two fatalities; a PT-17, ditto but no injury—suspicion of carburetor ice; and a Piper Archer in high density altitude with four people on board climbed to about 100 feet, stopped there, and stalled—serious injury to all on board.

The Air Safety Institute’s 24th Joseph T. Nall Report identifies that, in the pilot-related category, takeoffs rank as a high risk area and are far more likely to produce fatalities than landings. It’s a perfect set up for complacency to settle in because very few of us have ever suffered a mishap or failure on takeoff. Continental, Lycoming, Rotax, Pratt & Whitney, et al. perform remarkably well when properly maintained and fed.

It’s hard to get into the mindset that this is a high risk area of flight and one with few options. To use a financial metaphor: The airspeed/altitude bank is low on deposits and we may be called upon to make a large withdrawal with little warning. Sadly, there is no overdraft protection. Overspending needs to stop before it gets started. (Wonder if we could get our elected representatives to start thinking that way?)

If you’ll recall, Harrison Ford went off airport this spring after an engine failure in an antique aircraft that had been restored.

In multiengine flying a lot of energy is devoted to single-engine operations perhaps because the odds double of having an engine failure in a twin. Or perhaps it’s because piston twins don’t fly especially well on one engine. This isn’t to resurrect the old twin vs. single debate, but just to get us thinking about the takeoff no matter how many engines are on the aircraft.

Sometimes the powerplant telegraphs that it’s got indigestion, but wishful thinking prevails and the attempt to take off is made anyway. Hesitation, a poor mag check, backfires, fuel surging, low oil pressure, weird temperature indications, and sluggish acceleration are all reasons to rethink whether you really want to challenge gravity when the primary means to do so isn’t up to the task.

Having just completed a simulator session earlier this month, I was reminded that in training we are primed for everything to go wrong and generally on our best spring-loaded behavior to respond instantly. But in the real world that often isn’t how it happens. In practice, if the first effort is botched there’s always a do-over. Not so in most real-life takeoffs.

Once in a great while something just flat breaks with no premonition—but that’s rare. In my simulator scenario, the engine-driven fuel pump was rendered inop and the auxiliary fuel pump needed to be put in service immediately. Got it…on the do-over, and I’m thinking about it now!

Sudden vibrations and grinding/banging noises indicate bad mechanical things that a boost pump isn’t likely to fix. Good preventive maintenance will usually preclude such, but sometimes it’s just going to be a bad day. Work with it.

Pitch attitude needs to change from climb to glide quickly. Takeoff climb angle of attack (AOA) is just about perfect for a stall with the power off. Always, always: Landing under some semblance of control is better than lawn-darting into Mother Earth. That’s a mantra for every takeoff. Bob Hoover’s immutable wisdom comes to mind, “Fly the thing as far into the crash as possible.”

Overloading, density altitude, and improper configuration (flaps, fuel selector, etc.), and the occasional control lock foolishness are all opportunities for a very short flight. Leaving the planet is a big deal despite the fact we’re privileged to do it much more so than many other residents. Let’s give it the respect and preparation, mental and physical, that it deserves!

Any good takeoff stories to share? I’ll go first: One evening, while instructing, I had a Cessna 150 develop carb ice at full power in the summer time—a high dew point was present. Never had a slight power loss on takeoff before, so I tried carb heat. It worked!

Safe pilots are always learning, and the Air Safety Institute’s goal is to ensure pilots have a wealth of information to keep flying safely—like this Takeoffs and Landings Safety Spotlight. Help us to keep educating pilots on safety issues by donating to the AOPA Foundation today.

Bruce Landsberg,
Senior Safety Advisor, Air Safety Institute

ASI Online Safety Courses  |  ASI Safety Quiz