Unicom

January 2003 Issue




SB can be BS

Service bulletins are sometimes more legal defense than aviation safety

Your article “Pin Placement” [Accident Probe, November] questions the pilot/owner’s non-compliance with a Beech service bulletin.

One of my former jobs was as an engineer at a major airline. One of my tasks was to review the steady stream of service bulletins that came in from the aircraft manufacturer and evaluate whether to comply fully, partially, or not at all with a particular bulletin.

Most of these bulletins had the word “Mandatory” across the top in red letters. My office was run by a stickler for safety who would stand up to any airline management for something that had a true safety impact.

We complied with relatively few of the mandatory service bulletins that came in. The reason is simple: The cost of complete bulletin compliance would have been onerous and the safety impact was rarely significant or was already known and handled by another less costly means.

The truth is that many bulletins get escalated by the legal department of the aircraft or component manufacturer in an attempt to reduce their culpability in an accident. This factor presents the general aviation pilot/owner with a dilemma.

Service bulletins, instructions, notes and service difficulty reports serve up real information about what is going on in the field with your type of equipment, but few pilot/owners have their own engineering staff to sort the wheat from the chaff. As with the airline, most owners would find the cost of completely complying with every bulletin to be excessive and sometimes unnecessary.

Looking at the Beech bulletin through my former employer’s perspective one would clearly see the risk: “Having a gust lock that is not readily detectable is a serious safety risk.” This would lead to the question: “What are we doing procedurally? When, how often and by whom is a gust lock installed?”

The solution could be to limit the times when a gust lock is installed and make sure that any gust lock is attached to a big red placard or flag. Buying an expensive manufacturer’s part would probably not be the answer.

Why did the pilot install a gust lock during a quick turn? Unless the wind is howling, who installs gust locks during a fueling stop?

-Chris Burns
Via e-mail


You raise valid points about the true value of some of the service bulletins manufacturers issue. However, it’s important to note that the accident airplane’s gust lock apparently did not have any kind of flag and was simply a clip that held a pin into the bottom of the control column – not the easiest thing to detect on your standard flow check.

The service bulletin basically was intended to make the gust lock more visible when it was installed. We don’t necessarily take the accident pilot to task for ignoring a service bulletin, but for missing the implications the bulletin carried with it.

Why the gust lock was there during a quick turn is, at this point, anyone’s guess. The pilot also apparently neglected the oft-overlooked “controls free and proper” preflight check.

Finally, your question about the procedures in place is a good one. The proper procedure was already in place in the form of the aforementioned “free and proper” check, showing that even the best procedures are worthless if they’re ignored.

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Off, On – What’s the Diff?
Just read Thomas Turner’s article about airport lights [Systems Check, November]. I recently encountered a very unusual and potentially hazardous anomaly in the way PCL is handled at a particular airport here in California.

Atwater Castle (KMER) has PCL. But, if you look at the fine print, three clicks turns them on and five clicks turns them off! I had never heard of such a thing and kept trying to turn them on with clicking at different rates and amounts, each time ensuring that they stayed off.

Lovely, no?

-Jim Posner
Via e-mail

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Fast Walk? No Way
While I agree with letter writer Bill Rogers in “Slow Down, Pal” [Unicom, November] that taxi speeds should be reasonable, I have never bought into the argument that all taxiing should be done no faster than a brisk walk. At best, a brisk walk will cover a mile in about 10 minutes. When was the last time it took you 10 minutes to taxi the length of a mile-long runway?

Once away from the ramp area, taxi speeds should be dictated by aircraft type, wind conditions, other ground traffic and airport layout.

-Russ Johnson
Via e-mail

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Turnback Too
I read the letter from David Rogers, “Rethinking Turnback Strategies” [Unicom, November] about the turnback after takeoff technique. Having taken the BPPP course I was quite disturbed at the possibility of not having the best information. I contacted John Eckalbar instructor of BPPP and author of “Flying the Bonanza” and “Flying High Performance Singles & Twins.”

Wow, what a response I got from him. To be brief, John had a long and detailed and pointless discussion with David Rogers 10 years ago. The bottom line is the BPPP stands by their recommendations on engine out on takeoff.

Thought your readers would like to know there is another side to this issue.

-Ray Brown
Via e-mail


So, tell us more.

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Turnback Too, Redux
David Rogers takes issue with the Bonanza Pilot Proficiency Program’s endorsement of a turnback technique that is not as radical as his. I believe the BPPP adopted the target airspeed of 130 percent of stall speed as a compromise to fit the vast difference and skill and experience levels which exist in the American Bonanza Society membership. I still maintain that this more conservative approach to the problem of engine failure is a better way to go. My greatest trepidation is that someone will casually read Mr. Rogers’ letter and adopt 650 feet as being a safe “go/no-go” altitude for all conditions in an A36.

It comes down to risk management, and you said it yourselves in your reply to Mr. Rogers’ letter “Our biggest concern is that people won’t practice it and then will be incompetent when nibbling around stall speed in the bank.”

In most cases, a stalled and perhaps spinning airplane striking the earth in a nose down attitude poses far greater risk to its occupants than a controlled level touchdown. In any event the purpose of my original letter was to express concern about the fact that a lot of pilots don’t seem to have a plan of action for this situation.

-Jim Piper
Palos Verdes, Calif.


Just as Mr. Rogers’ technique cannot be applied to all situations, neither should the Bonanza Society’s. There is a problem with generalizing in a world filled with ambiguities, as this illustrates. Rogers’ technique provides what our own flight testing agrees is the best the airplane can do with a pilot who is practiced at the technique. Your mileage may vary, however, and if you choose to use a more conservative but less capable technique, that is certainly your option.

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Point Taken
I will get to the point. I have been a subscriber to your publication for some time and find your writing staff not only knowledgeable, but also entertaining. We all know that flying is an education that doesn’t have a graduation, a passion never satisfied and a fraternity to be proud of.

I read your journal from cover to cover and want to thank you for making me a little smarter and a lot safer.

-David M. Palmieri
Crestwood, Ky.


Stop it, we’re blushing. Actually, don’t stop it at all.

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Spin Resistance
I realize this is a bit of nit picking, but in your response to “Spin from a Slip?” [Unicom, October] you write, “A slip during descent is usually OK because the airplane is descending, which helps unload the wings.”

Unless the angle of descent or climb is severe, the load on the wings of a steadily climbing or descending airplane should be the same as an airplane in level flight, the full weight of the airplane.

An airplane with an increasing rate of descent has a lighter wing load than in level flight, so I let the airplane descend when I must make a tight turn at low airspeed.

I took a Cessna 152 and my own Cherokee 140 up to a safe altitude and gradually pulled the stick back in a “typical” crosswind slip. In both airplanes, the slip turned into a mush rather than a spin.

Of course, a pilot low and slow on final should be vigilant about airspeed, but there are some airports (Palo Alto comes to mind) where wind shear on short final approach is a common phenomenon.

So it is nice to know the airplanes I’m flying do not spin easily.

-Adam Rosenberg
Atlanta, Ga.


Hmm. Don’t you say in your third sentence essentially what we said in our sentence you quoted? The nuance, increasing rate of descent, is a seat-of-the-pants experience that seems intuitive in flight to us. The spin can come if the pilot allows the ailerons to drift to neutral at the stall while keeping the rudder cranked in, at which point it spins over the top, or opposite the direction of the bank. Perhaps this graphic, which originally ran in July 2002, will help.