WWI Replica Safety

Sweb · 6 February 2009, 01:12 PM

An established preflight, postflight and periodic inspection and servicing requirements should be built into the plane while on the drawing board. Periodic intervals should be established on the known weakest part (mean time between failures) of the craft whether it is a specific part or system or structure, etc. The minimum equipment list (MEL) should become a study for establishing just that.

In other words, the plane is built, operating, serviced and being maintained in your head before and during the build. Everything new (reverse engineered when historically important) that are not standard aeronautical parts and fabricated from local specifications should be assessed for their functionality, structural integrity and limits as appropriate. Reliability checks and assurances are part of the build.

Safety being the prime mover here, design a program for the craft on the drawing board, take photos along the way and incorporate the photos and instructions into a manual with all the red bullets and alerts where they should be.

j ferguson · 7 February 2009, 06:04 AM

Likely, operators of replicas will never get calls from the shop. They will be there at the tear-down.

But....

I left out a critical element in calls from the shop at PWK. A really bad call always started with "Has it been a good day so far?" What this meant was that my airplane had evolved from a questionable asset into a definite liability.

I asked Gene why he did this. He said they taught it at A&P school.

They probably use the same script when you get an adverse report from a biopsy or the blood lab.

Sweb · 7 February 2009, 10:30 AM

Quote:

Originally Posted by j ferguson

Likely, operators of replicas will never get calls from the shop. They will be there at the inquest,

But....

I left out a critical element in calls from the shop at PWK. A really bad call always started with "Has it been a good day so far?" What this meant was that my airplane had evolved from a questionable asset into a definite liability.

I asked Gene why he did this. He said they taught it at A&P school.

They probably use the same script when you get an adverse report from a biopsy or the blood lab.

You may also know it as the Gravestone Mentality. A safe airplane is only a concept, like a theory, until proven as fact. This is where I put the skids on anything I'm unsure about, study it, establish any changes if necessary and then move on. Even Warren Buffet by his own admission never buys a stock he doesn't understand. I was at Elsinore many years ago when a man died flight testing an Experimental. The designer claimed the wing was capable of 4 G's and the post-crash investigation showed it shed its wings at about 1.5 Gs. That's an extreme case of the blind leading the blind, Gravestone Math. I was a kid (14) and flew there with my Pop from Orange County Airport for a look around. I never forgot that. I even take it to a safer level with R/C 1/4 scales I build if something looks structurally lame in a kit.

j ferguson · 7 February 2009, 11:46 AM

I was thinking of the defective airplane, certainly not a departed pilot. Sorry for an unclear thought.

Joe Perkel · 7 February 2009, 03:27 PM

Quote:

Originally Posted by Sweb

I put the skids on anything I'm unsure about, study it, establish any changes if necessary and then move on. Even Warren Buffet by his own admission never buys a stock he doesn't understand.

The above statement is quite profound, and very applicable here. I continue to be haunted by some questions and doubts about the design of the aft spar center section to wing panel junction. Things such as minor but stark discrepancies in the drawings, and little alignment nuances here and there discovered in the course of CAD modeling. Not to mention the sharp transition zones (rabbets) which were taught to me as stress concentrations in A&P school. I must at some point, fully understand the design intent.

I've never quite thought of how an investment mindset can be applicable here, but the Buffet analogy is one I will remember!

Despite the occasional "Bouncing Betty", this forum continues to produce nuggets of gold here and there!

Thank you!

Flysafe · 11 February 2009, 05:43 AM

SWEB, good points, with the caveat that anything developed during design and construction is theoretical and while providing great guidance may not perform as designed in practice.

This happens all the time with certified aircraft! As I have stated earlier in the thread the two fundamental problems we face with replica aircraft are that, none are built 100% to a consistent standard specification, so they are all "one of" models and unlike certified aircraft we lack the required business processes to capture and track "service difficulty reports" and share our in service failures with our small and widely spread community.

A further challenge we face is that each individual aircraft does not fly many hours so the individual and total in-service experience is low. At the GWFM with seven aircraft we still do not fly large number of hours, averaging 150 hours per year TOTAL for the fleet, and in recent times reducing due to high fuel prices, aircraft out of service and a drop off in available airshows. That is high when compared to many private owners and even with this in-service experience new and unique challenges come up all the time. One advantage we do have is that the lessons learned on one aircraft can, in many cases, be transferred to the remainder of the fleet. That being said each individual aircraft has its own unique problems that can only be detected with good inspection practices.

The net result is that we lose "three layers of safety" and must compensate with increased diligence during periodic and preflight inspections.

Having been around a number of different replica aircraft for over 20 years I can attest to the fact that in service problems are regular and require constant vigilence to detect and fix and you can never let your guard down. As soon as you think that you have an aircraft problem solved you need to start looking for the next problem.

Joe Perkel · 11 February 2009, 08:45 PM

It would seem that some guys are just a bit passionate about safety.

I wonder how this fellow might feel about our little thread here?....

Safety Reliability Methods, Inc. - About Us

No checklist or procedure for this save,...no no, this one was between the ears prior to push back.

Sweb · 22 February 2009, 05:23 PM

Quote:

Originally Posted by Joe Perkel

It would seem that some guys are just a bit passionate about safety.

I wonder how this fellow might feel about our little thread here?....

No checklist or procedure for this save,...no no, this one was between the ears prior to push back.

Yea, maybe so. I'm of the school of thought that "when in doubt, don't". I come from an aviation family of flyers and was taught to put the joy of flying subordinate to everything else. I'm quite sure that is the philosophy here as well and I've been lucky to have worked with many professionals in my time. Maybe I've just seen too many incidents.

I had a job for 5 years salvaging wrecks of commercial airliners after the various national authority accident investigation teams were done with them. The job took me into various corners of the globe and into very remote locations. I was 27 when I left that job but a lot older than my years. All of the salvages I performed were the results of human error. That pretty much drove the point home. Call me a product of my experiences. I do relax occasionally, though!

Machinbird · 15 March 2009, 08:16 PM

I thought it might be a good time to discuss directional control in tail draggers, especially since I found a good discussion piece on Youtube. The aircraft is under good control until its cross wind limits are reached and then even full rudder is not enough to keep it from changing direction. What should we as builders and pilots be doing to avoid making expensive kindling wood? I am not making fun of this pilot's skills. He has done well with the tools he had at the moment, but the potential for serious damage to the airframe was there.
What are your thoughts?
Sid

YouTube - Why Not Land Your Fokker Triplane in a Crosswind?

Joe Perkel · 15 March 2009, 09:22 PM

Quote:

Originally Posted by Machinbird

The aircraft is under good control until its cross wind limits are reached

What are your thoughts?
Sid

Sid,

I'm going to rename you "Merlin" as I was thinking of this just today!

Here was today's wx here in Miami.....History : Weather Underground Note the wind gusts 18 to 24. It was a beautiful sunny day here, and I thought to myself that it sure would be hard to resist the temptation even though I know it would be a bit choppy out there.

- Resisting the temptation on an otherwise seemingly perfect day....very, very tough to do! Notice the sound of the wind on the microphone, although the brief glimpse of the wind sock it doesn't seem so bad.

- Just reading up on inspection issues, and a wingtip ground contact incident requires a thorough look-see for compression cracks along the spar. Particularly at the strut attach points and at the root. These can be masked by the hardwood pillow blocks used at the struts.

That, was one of the most superb looking DR.I's I have ever seen!