787 lightning protection

Dominic Gates at The Seattle Times had a long story Sunday (Feb. 8, 2009) about the Federal Aviation Administration relaxing rules on lightning strikes as too stringent and which the new composite Boeing 787 cannot meet.

The rules, adopted following the in-flight destruction of TWA Flight 800, a Boeing 747 (which crashed for reasons other than originating with a lightning strike), could not be met by other manufacturers, either, according to the Gates story. What we find eyebrow-raising is that the FAA proposes changing the rules to permitting only one system for lightning protection, abandoning the decades-long concept of redundancy for safety.

You have to read the Gates story for the details and why the FAA thinks this move is OK in the case of the 787.

But we’ll point out that there is a recent example of an aircraft design without a second back-up system leading to a fatal crash: Alaska Airlines Flight 261, when the McDonnell Douglas MD-83 lost control, inverted and crashed into the Pacific Ocean when the vertical tail’s jackscrew failed. This system controls the horizontal stablizer on the top of the T tail. Alaska, with approval of the FAA and Boeing (which by then had acquired McDonnell Douglas), changed suppliers for the grease and the maintenance interval for the jackscrew. This proved a mistake; the new grease wasn’t as durable as the old. Then the grease wore out, the jackscrew failed and because there wasn’t a second system, the flight crew lost control of the airplane. Everyone was killed in the ensuing crash.

Lightning strike protection has been a vexing issue for Boeing for several years. Gates wrote this story about Boeing’s challenges in 2006. In that story, and the one Sunday, fasteners play a key role in the concerns that lightning could ultimately result in igniting fuel in the tanks. As readers know, fasteners have been particularly troublesome for Boeing on the 787, for a variety of reasons unrelated to this issue. In 2007, former CBS anchorman Dan Rather, in his new job as anchor of start-up cable channel HDNet, touched on the lightning strike issue in a larger report about the safety of composite airplanes. The report was widely met with derision because Rather had recently left CBS under a cloud of credibility issues and he relied on a former 46-year Boeing employee who had been fired for the foundation of his report. We had this report at the time.

There is, of course, no benefit to Boeing to engage in shortcuts or crimp on safety. But we have to admit we’re concerned about having only one system and not redundant systems for lightning strike protection. The need for back-up systems was amply illustrated with the US Airways Hudson River landing. When both engines were damaged and essentially lost power–only a small amount of thrust remained after the bird strike, investigators now know–the RAT, or Ram Air Turbine, kicked in to provide power for vital controls. Back-up systems have been at the core of aviation safety. The FAA’s proposal to do away with them for the 787 is worrisome.

Update, February 11: Boeing provided a response to this entry, which we have posted in the comment section on its behalf. Please be sure and read Boeing’s comment.

8 comments on “787 lightning protection

  1. Fasteners are directly related to this issue.

    Fasteners make 787 commercially possible.

    Let me explain:

    As you may well know, carbon reinforced stuctural components are are made up of many layers of carbon fiber tape. Within the tape itself, the fibers are linear, and run longitudinally.

    When a high energy electrical pulse strikes the fibers, the current travels to the end of the fiber, where it can jump any gap to the end of the next nearest fiber. The ends of the fibers in the gaps may get hot or even burn.

    This includes the gap created by every single fastener hole.

    This is overcome by an interferance press fit of each fasttener, and perhaps an adjunct of carbon bearing sealant.

    In the past, each hole was a close tolerance fit, requiring extreme care in the drilling of each hole. The hole must be straight, concentric, and of precise diameter.

    Boeing chose to overcome this with a new fastener design, that expands to fill the hole, provide the neccessary interferance fit (and thus electrical path)without crushing or deforming the composite, and without some (not all by any means) of the drilling/installation fuss. Without these, Boeing would be looking at production costs that would sink the program.

    Nevertheless, you still have to ensure that each of the thousands of these fasteners are installed with great care and precision, and that’s the rub. That’s why you need multiple systems for dealing with lightning strike.

    Fuel cell inerting is a system.

    Mechanical devices (ground jumpers, electrical bonding techniques) are a system.

    And these fastteners are a system as well.

    You have the additional problem of increased static build up and discharge in the largly resin/graphite structure.

    The you add the engineering problem of ensuring electical continuity between plastics and metal components.

    So what do you have? FAA engineers being overridden by FAA beaurocrats apparantly. With a great deal of weight from the party of interest, namely Boeing.

    Who do YOU trust?

    And it’s been asserted in other venues a number of times that FAA ‘cooperation’ in regards Boeing is quite lavish, lavish enough to raise questions.

    In Boeing’s favor, it probably has the greatest amount of experience in the world with large, carbon fiber/resin aircraft structures of anyone.

    But it all comes back to those FAA engineers…….

  2. We received this note from Jim Helms of the firm TATSCO. He authorized its publication.

    I appeared on NBC Nightline about two weeks after TWA 800. I had a week to prepare for the interview .. . “If it wasn’t a Terrorist Act what could have caused it?” We reviewed Boeing Service Bulletins and Airworthiness Directives. I selected two likely scenarios – A Bleed Air Line from the APU that had problems in the area of the aft wing spar OR a blown main landing gear tire (such an event brought down a Mexicana 727 shortly after take-off from Mexico City in the late 1980s). NOTE: The lightening strike referred to in the Times Article was a Pan AM 707-121 at Elton, Maryland in the 1960s. The current FAA requirements for Fuel Tank Safety include protection from lightning and faulty wiring – defective wiring or electrical equipment can create a lightning like spark. And the 10 days of operation without the inerting system . . . will it be noted on your ticket?
    .
    I viewed unreleased TV footage at NBC prior to the taping of the interview to reinforce my opinion. The formal NTSB Report convinced me further that a tire on the RH body landing gear may have (it was never found) exploded, damaging an electric fuel pump mounted on the rear wing spar — adjacent to the mentioned tire — the pump wasn’t found either.

    I met Bob Francis, the NTSB guy in charge, on two occasions after the accident; we were alone at the time. He sorta’ accepted my theory the first time and on the second encounter – mid 2001 in the Executive Club Room of the Regal Hotel at Hong Kong Intl. he went further — “what could I say . . . it was the ‘desired’ finding!” You may remember it was shortly after Richard Clark, Clinton’s Natl. Security guy, came to Long Island that “the team” released their finding – “bad wires” (Clinton wouldn’t touch terrorist ideas shortly before the 1996 election!).

    About three years ago – when the FAA was trying to justify changes to the regulations re Fuel Tank Safety – I wrote a second NEWSLETTER article about TWA 800 – “it wasn’t wiring . . . “. Shortly after, I received a call from the brother of a U.S. Senator – Jim, my brother doesn’t like your theory re 800 – please cool it!

    Well, the FAA has put the changes to the fuel systems/tanks “on the books” – air carriers have modified airplanes and people have sold 727 business jets (they have post production Aux Fuel systems that don’t meet the requirements of the proposed changes to fuel tanks/systems). I don’t believe the FAA has granted any petitions for an Alternate Means of Complying with the new regulations.

    Derek Yates and others have responded to Notices of Proposed Rulemaking – NPRMs – re the fire hazards of the 787 primary materials. Ali Bahrami has dismissed all of them – “outside of the scope of the NPRM”. FAA ATLANTIC CITY, the USAF, the USN, and the AUSTRALIAN Civil Aviation Authority agree — CFRP aircraft burn – they contain highly combustible epoxy resins that can burn (and produce toxic smoke) for hours after the aircraft fuel load has burned away.

    I have sent copies of the TIMES article with my comments to Doug Anderson, FAA Renton Legal. I have corresponded with him re the fuel system Airworthiness Directives and he has been a NEWSLETTER reader for several years.

    Oh, by the way, last summer I looked at the FAA’s Type Certificate Data Sheet for the Hawker Beechcraft business jet – and confirmed with a friend who is an Airworthiness “guru” at Beech – there were no exemptions or other reference to composite materials in certifying the Hawker Business Jet. I haven’t researched the Falcon 7X yet. It uses “composite wing panels” – here is no reference on the Falcon web site re composite structural parts, i.e., wing spars/ribs.

    The hard-to-deny objection to what the FAA has proposed is the concern expressed by the 190 engineering folks at FAA Renton. They work for Ali.

    JIM

  3. I think the fuel tank inerting will go a long way to preventing any related issues.
    What does concern me however is that in the event of an unservicable inerting system, an aircraft can continue revenue flying for ten days before it must be fixed.
    As Murphy puts it so eloquently “if it can happen it will”

  4. We received this response from Boeing today to our posting, with a request that it be viewed as a Letter to the Editor:

    Mr. Hamilton,

    Your blog entry of Feb. 9, 2009, entitled “787 lightning protection” missed several key points. First, the FAA and industry have concluded that certain aspects of the structural lightning protection requirements contained in their regulation are impractical to design to. The 787 design will comply with the revised policy memo through a combination of rigorous fuel tank lightning protection design requirements and meeting recently mandated stringent flammability exposure standards in the fuel tanks.

    Second, the 787 will be as safe, or safer than, today’s airplanes. That requirement has not gone away. Your blog indicated there is not a redundancy system in place. That is incorrect. There is redundancy and independence at the overall system level, consistent with long-standing aerospace design norms. We will comply with all requirements documented in a specific FAA special condition, based on the policy memo, for the 787. In fact, we have been introducing new technologies such as fuel-tank inerting on the 787 and other production airplanes that will further enhance the safety of the airplane.

    We are required to demonstrate compliance through extensive testing and safety analysis that the design of the airplane precludes failure modes which would lead to a fuel vapor ignition during the life of the fleet.

    Thank you.

    Yvonne Leach
    787 Corporate Communications

    Our Comment: We didn’t go into the detail Boeing refers to in this response, instead specifically steering readers to Dominic Gates’ story for the detail and rationale.

    We’d be a lot more comfortable if the fuel inerting system is an MEL item (Minimum Equipment List), but according to The Times story, it’s not.

    Thanks very much to Boeing for its comments.

  5. The Leeham net comments regarding the Boeing response hardly engender confidence in this blog’s claim of “Intelligence for the Aviation Industry”.

    Here’s a quick clarification for our “industry experts”: When an airplane system is inoperative, and that system appears in the MEL (Minimum Equipment List), this means there is some degree of dispatch relief available. So, if the inerting system appears in the MEL, an airline would have 3, or 10, or even many more days of legal authority to fly the airplane with the system inoperative. On the other hand, items not found in the MEL have no dispatch relief. If an item not found in the MEL is inoperative, the airplane cannot be legally released to fly (at least not on the authority of the MEL).

    The level of dispatch relief contained in the MEL is a result of intense fault-tree analysis and a collective study performed by Boeing, airlines, suppliers and the FAA, over a period of several years. It’s a science, not a pay-off handed under the table from a corrupt regulator to greedy OEM. The Leeham response reveals an inverted and incorrect understanding of how the MEL is developed, as well as how it is used by the industry.

  6. Congratulations, Mr. Hamilton, for getting the rare comment from Boeing’s spin department. My blog has been up for years and has never gotten that distinction, even though Boeing and their synchopants visit it frequently.

    I see that Boeing’s (as usual) fact bereft PR spin did not change your informed mind on the subject of the nitrogen inerting system S/B MEL status, which is a credit to you.

    Boeing PR, however, has not done itself any credit in recent years in its heavy use of obfuscation and diversion from the truth in its releases. You only have to look at the “factuality” of the first four 787 delay announcements to see that. Now, Boeing and its PR department have next to no credibility it seems. I covered “Boeing credibilty” in detail on one of my blogs and won’t go into the sad details here. Sadly, now you have to err on assuming Boeing PR releases are lie ridden, if you are not to be fooled yet again. But they are responsible for that via their attempts in seemingly every release to spin untruths into “truths.”

    Enough about the sad subject of Boeing PR and Boeing’s other censorship and message control activities.

    You and your readers can read my brutally honest comments sent to the FAA on the proposed policy change on my blog at:

    http://eastmans.web.aplus.net/pblog/index.php

    Thanks to everyone who so truthfully and wisely commented here (except Boeing, of course).

    The source of this problem (as well as myriad others) is the Boeing /FAA management corruption I began to try to stop in 2002, but tragically continues to this day.

    It only requires minimal courage on the part of someone or some agency with the power to stop this corruption to begin the necessary efforts to stop it forever. So far, however, those in that possition have been cowed from doing so for whatever reason.

    Gerald Eastman
    The Last Inspector

  7. We don’t generally respond to reader comments unless there is a direct question asked of us, but we feel compelled to comment on Mr. Eastman’s item.

    We’ve certainly had our disagreements with Boeing’s PR machine, both privately and on rare occasion publicly. But we feel Mr. Eastman’s condemnation of the PR machine is a bit harsh. They work within the parameters they are given and sometimes are the last to know on any given issue, leaving them in the uncomfortable position of finding out things from the media before they find out about things from their own internal channels. This sometimes leads to putting out information that later is demonstrated to be incorrect.

    Mr. Eastman speaks from a different level of experience on different issues. Our experience, though often frustrating for entirely different reasons, nonetheless doesn’t lend us to question the integrity of the communications staff, many of whom we’ve dealt with for years. These are dedicated people whose job it is to promote and protect Boeing. This sometimes is at cross purposes to others, including journalists and bloggers.

  8. Mr. Hamilton. Your opinion on the subject is noted.

    However, I do indeed have a different perspective. For instance, [name deleted by Moderator] attended the first several days of my trial, and we exchanged some polite banter in the restroom concerning the 787 delay announcements. I commented to him that they must be worried about having to announce another 787 delay. His response was minimal, other than to acknowledge the unpleasantness of the subject for them (this was just before the third 787 delay announcement).

    Yeah, it would be nice if Boeing PR didn’t know they were being played by Boeing management. But unfortunately, they are not just dumb announcers–they participate in gaming the press themselves. There may be such innocent employees in Boeing PR, however none of them who interface with the press qualify for that status. True, they are nice to the press until they perceive the press has strayed from Boeing’s message. In that case, they will turn on you and bring that whole media outlet to their knees.

    Thanks for your response, and thanks for bringing some independent opinion to all spin Boeing.

    Gerald Eastman
    The Last Inspector

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