Posted on 04/11/2008 4:48:54 AM PDT by Gamecock
I didn’t know Boeing manufactured the McDonnell-Douglas MD-80.......................
They do now. McD-D is part of Boeing
Mc Donald was bought by Boeing.
I knew the CEO of Mc Donald that was retired out when they were bought and still do work on their home in Rancho Santa Fe.
Sorry to say, he died of pancreatic cancer a number of years ago.
First, obviously, is to support the cable(s) during all anticipated g loading. It probably does not matter if the spacing is 1 inch, or 1.25, or 0.75... There is probably plenty of strength. Exactly 1 inch sounds like a nice round number for the convenience of the assembler and inspector, not an exact engineering requirement.
Second, is so that the cables don't flex, rubbing against other cables/wires in the assembly or any nearby structures and abrade through insulation. This requirement is there for the long haul. A few more hours flight time with marginal ties isn't going to make any difference. If you're looking at thousands of hours over the lifetime of the aircraft, yes, you want to minimize this effect. But a dozen more hops? I doubt it would make any perceptible difference.
I think AA got it in the shorts from the FAA. I'd have flown on any of those aircraft...
It would not be unusual for this to have some surprising consequences.
But engineering requirements don't matter if you're a power-mad bureaucrat trying to show the productive and profit-earning people, who for some unfathomable reason have to do what you say, who's boss.
As a former QA instpector in a past life (on submarines, not aircraft), there is no there is no room for interpretation and there are no optional steps.
Yeah, it was a pain to make sure exactly three threads showed past a bolt, or that lockwire had the requisite number of twists per inch, or that fastener materials were the exact same material.
As a result, I could go to any ship and look at any boundary whether it was a hull valve, a dynamic seal, a dashpot or whatever and know for fact though audit trail and visual inspection that work was done the exact same way everywhere. Since my number of dives are exactly equal to my number of surfaces it must’ve counted for something, which I can’t say for a lot of folks from the days when QA wasn’t quite so rigorous.
You can bet China doesn't have a bunch of nosy Federal bureaucrats looking at the way they make toys, drugs, food, aircraft ...
Could be about something else altogether, if you want to be paranoid. Could be a cover to check to see if some folks were planning on leaving something additional in the aircraft...maybe go boom. Just a thought cuz the stated reason seems a bit of a stretch.
Bad, bad computer.
While I understand your comment, the underlying concept in this AA case is wrong. The wire-ties will not prevent chafing, merely delay its onset. Correct prevention would require a different method of passing the required signals between the points of contact; a larger conductor with a heavier insulation, a separate enclosing insulating cover, re-routing to prevent any flexion.
The three-thread indicator shows that the correct torque was in place, and verifying that the spacing of the internal space was within a set allowance of part compression. Likewise, the lockwire relies on tension to verify that the wire itself is correctly tensioned and holding the nut from vibrating free. Different materials provide for different tolerances of torque.
The wire-ties don't do any of those valid attributes, they are necessary, but should not be used as a safety item.
This was another in the long line of government bureaucrats exercising bully-boy tactics that have no valid reason besides a show of force. AA should have pushed back, and flown.
Yes and no. Again, we have to look at the details, here (the devil's always in the details). The point of the requirement was to prevent wire chafing around the landing gear mechanisms. Cable ties or no cable ties, if there is constant rubbing of any component against a wiring bundle, over time, you will get chafing and wear.
According to the article, the inspections showed that with/without the new requirement, chafing was occuring. To avoid the potential for chafing, the wiring bundles would have to be re-routed away from the source of the chafing (i.e. the landing gear mechanism); simply adding cable ties every inch and orienting cable clamps on't do anything to prevent chafing/wear if the bundle is not removed from the source of the chafing. To do that would require all new wiring bundles to be installed that would take the A/C out of service for a longer period of time because, in most cases, wire splices are not permitted by the FAA. Wire bundles in aircraft tend to have almost zero extra length and tend to comply with very strict length requirements.
So, again, this is all for show and the FAA is just flexing its muscles to prove that it can. But, here's a question for you - How many politicians or FAA officials do you think were inconvenienced by this? My bet is NONE.
“there is no there is no room for interpretation and there are no optional steps”
Agreed. I think that attitude is why we haven’t lost a boat in a long time.
Having worked under guys like you, I wasn’t always too happy about this attitude, but I always understood it!!
Not to be contrary, but I see it the other way around. Making a further exception to the rule would be the result of some individual in the FAA flexing their muscles - and bypassing the plain meaning of the ruling. The inspections were either not done or done improperly. They are overdue.
I fail to see how enforcing a ruling in the face of violations of the ruling is "flexing muscle". It's a matter of compliance (in the certification sense of the word).
The FAA was **seriously embarrassed** by letting SW sluf on exterior crack inspections - they (FAA) were accused of being too cozy...
How do you ‘prove’ you aren't too Cory?
Why screw the next guy in line of course.
It's about EGO, not safety....
QA is a nice thing, too many things tend to fall off of aircraft otherwise.
Exactly!
If it were submitted to the FAA with spacing at a minimum of 10' apart and approved the issue wouldn't exist.
If they vary from approved data then it has to be submitted and approved again.
If not, then what good does it do to have approved data in the first place?
Just toss the aircraft together any way one deems fit personally and hope for the best?
Many within the FAA however if there were to be an incident because of the variance and those PMI's within the FAA let it ride unchecked.
I think I’ve asked this before, but is your screen name a reflection of what you do (or have done in the past) for a living? And are you in the Redmond area (I’m based near Kansas City, myself, working in the aircraft systems certification arena).
Yes and no in that order.
It's my butt if something happens to an aircraft after I have deemed it to be airworthy by a simple (sarc) signature.
I do design approvals (TSO software). I know what you mean!
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