Sept 19th, 2000
Jet's Troubled History Raises Issues For the FAA and the Manufacturer

By ANDY PASZTOR Staff Reporter of THE WALL STREET JOURNAL

LONG BEACH, Calif. -- What do you do about a jetliner that passed all airworthiness tests, has been flown for almost a decade by several major airlines and has been improved many times -- yet just keeps giving trouble?

It's something that regulators and two successive manufacturers have had to grapple with for years regarding one of today's jumbo jets: the MD-11.

Introduced by McDonnell Douglas Corp. in 1990, the plane had computerized flight controls that were supposed to offer a big advance in safety.

Instead, the MD-11, with problems ranging from early computer and electrical glitches to finicky handling that makes it tricky to land, has become the focus of concern within the industry.

The big jet "is a terribly, terribly unforgiving airplane," says John Goglia, a member of the National Transportation Safety Board, which investigates accidents and makes recommendations to the Federal Aviation Administration. Twenty-one times, the tail of the 202-foot-long plane has struck the runway during takeoff or landing, with damage ranging from superficial scrapes to the buckling of structural supports.

Worse, five of the global fleet of 198 MD-11s have been destroyed in crashes. That makes the MD-11, statistically speaking, more prone to crashing than any other modern jetliner.

FAA Calls It Safe

 Four of the crashes have come in the past two years, including a Korean Air freighter that mysteriously plunged to the ground shortly after leaving Shanghai and a China Airlines MD-11 that crash-landed in a typhoon at Hong Kong's airport. The Swissair jet that crashed in the sea off Nova Scotia, while full of smoke of uncertain origin, was an MD-11. "For such a new design, its safety record is out of the ballpark," the NTSB's Mr. Goglia says.

But in a crucial point, the FAA and Boeing Co., which became the manufacturer in 1997 by acquiring McDonnell Douglas, both declare that the MD-11 is safe. The FAA "doesn't have any particular concerns" about the MD-11, says Ronald Wojnar, the agency's deputy director of aircraft certification.

 

Subject: WSJ

/Jet's Troubled History/continued

 Yet sometimes, at low altitude, the opposite occurs: Pilots tell of pulling with all their might and finding the plane hardly responded. That can be a problem during landing. In several instances where pilots brought down their MD-11s too rapidly and tried to compensate at the last minute, they smacked the aircraft's tail on the runway or caused other damage.

That's what NTSB investigators reckoned took place in 1997 when FedEx pilots tried to land an MD-11 at Newark. The plane touched down too hard, bounced, rolled right, broke its right wing, flipped over and was destroyed by fire. The two pilots, who escaped, took most of the blame. But the safety board also raised questions about the plane's "stability and control characteristics," the design of its landing gear and why its wing broke off, a rare occurrence in similar hard-landing accidents.

Boeing acknowledges the tail-strike problem but says it has addressed the matter in a variety of ways, including new software and better pilot-training programs. It says there hasn't been a serious MD-11 tail strike reported in the past year or so.

'Just Quit Flying' Veteran FedEx captain Jack Burke, who once walked away from an MD-11 tail strike, has described his caution about flying the plane. "The first 100 feet and the last 100 feet are where the crew really has to sweat it," he says. If the descent isn't exactly right, Capt. Burke adds, he will abort the landing, because "the plane can just quit flying on you. There is simply no time to recover."

Some pilots, reflecting the joking camaraderie of their ranks, have adopted macabre nicknames for the MD-11. "Death Star," some facetiously call it, according to the Air Line Pilots Association's safety-committee chairman. Others call it the Scud, after Iraq's unpredictable Gulf War missile.

The MD-11's elaborate computer system has also been troubled in the past.

American Airlines executives recall having to park their first batch of MD-11s for several weeks because crews couldn't complete FAA-mandated flight tests. They kept getting electronic warnings -- which turned out to be bogus -- of maintenance problems. Delta officials were so peeved by such glitches they demanded that Honeywell, which supplied the MD-11's electronic brains, put a trouble-shooter aboard every MD-11 flight in the first months of service. A spokesman for Honeywell International Inc. declines to comment. The calibration bugs were gradually worked out.

But others followed. In the mid-1990s, McDonnell and the FAA began getting reports of the inadvertent high-altitude deployment of slats, the panels that slide from under the front of the wings and are normally used only during takeoff and landing. The result was a sometimes-violent swooping of the aircraft as surprised pilots tried to regain control. It turned out the handle to move the slats was situated where it could easily be bumped. At the FAA's and NTSB's urging, McDonnell re-tooled all MD-11 cockpits to fix the problem.

Then, carriers began complaining of numerous other flight "upsets" at cruising altitude, prompted by turbulence or pilots inadvertently overriding the autopilot system. The captain of American Flight 107 over Rhode Island on July 13, 1996, pulled back on his control yoke to make sure his plane stayed within its assigned altitude of 24,000 feet without first disconnecting the autopilot. When it abruptly disconnected and the pilot continued pulling, he later reported to the NTSB, the plane went into a series of wild dives and abrupt climbs. A similar incident took place on a Japan Airlines MD-11 a year later, this time seriously injuring a flight attendant and three passengers. According to investigators at the time, such roller-coaster motion could last for minutes.

Boeing and McDonnell before it have worked hard over the years to identify problems with the jet and fix them quickly -- usually acting before regulators demanded it. "We look at every incident, every idea, and don't let [federal] rules prevent us from making any improvement," says Ronald Hinderberger, Boeing's director of commercial aircraft safety. It is common for planes to receive numerous refinements after they first hit the market, and many troubles that have dogged the MD-11 over the years now are in the past.

The MD-11 is a difficult balancing act for Boeing, which inherited a plane that it hadn't designed and that competed with its own models. Lack of orders led Boeing to decide 2 1/2 years ago to phase out production of the MD-11. Even as it works to keep existing ones flying safely, Boeing wants to avoid giving more ammunition to critical pilots or to lawyers claiming tens of millions of dollars in damages on the grounds that design flaws are at least partly responsible for MD-11 crashes.

Comparison With Rivals But Boeing's Mr. Hinderberger acknowledges that the MD-11's accident rate is "abnormally high," which he says surprises him. His Boeing predecessor, John Purvis, says that compared with other planes designed around the same time, the MD-11 "shouldn't have this many accidents."

Normally, each new generation of airliner crashes less frequently than past models. Yet in aircraft losses per million departures, a standard industry yardstick, the MD-11's record is more than 10 times as bad as the Boeing 747-400, introduced in 1989 with some similar technology, and 15 times as bad as some older 757 and 767 models. It is about the same as the

707 and the DC-8, planes that began flying decades earlier.

What makes the case difficult is that there is no unified theme in the incidents afflicting the MD-11 over the years. Its worst accidents have had varied causes and often involved elements of pilot error. "It is frustrating that you don't see a common thing to go after," Mr. Hinderberger says.

That puts regulators in a difficult situation, adds his predecessor Mr. Purvis, now a Seattle safety consultant. Mr. Purvis says the MD-11's record "raises tough questions of what is safe enough."

As such, it focuses attention on the standard regulatory approach in dealing with a problematic airplane: piecemeal identification of flaws followed by a flurry of inspections or modifications. With this plane, seemingly each time a shortcoming has been addressed, some new one has emerged. Still, about the only regulatory alternative left would be to ground the plane. Not only is this a step the FAA almost never takes, but doing it when there is no specific mechanical flaw would be tantamount to acknowledging that the agency failed to detect fundamental design shortcomings in the original approval process.

The FAA says it has never considered grounding the MD-11. Throughout the aircraft's decade in the air, the agency has ordered dozens of specific fixes aimed at making it safer, says Mr. Wojnar, who adds: "I don't know of anything we'd do differently."

To help crews get used to the MD-11's handling eccentricities, Delta took the unusual step of urging pilots to fly MD-11s manually from takeoff all the way to cruising altitude, instead of making a quick switch to autopilot.

In the case of the autopilot disconnect, the NTSB concluded that pilots should be specifically trained not to overpower the system. The FAA called on the manufacturer to modify flight controls to keep the dangerous swoops from recurring. This summer, Boeing began offering revised flight-control software free to all MD-11 operators, intended to make the planes less sensitive to pilot input at certain low altitudes.

Throughout all of this, pilot representatives prodded regulators for more-aggressive steps. While the FAA and the original manufacturer, McDonnell, argued that pilots were mainly at fault, unions contended that inherent design features sometimes made the MD-11 too tough to handle for the average commercial pilot. "It is easier and less expensive to blame the pilots," says Michael Weiland, president of the pilot union at FedEx, "than to invest in design modifications and more rigorous safety and training programs." Some critics of the MD-11 think its record hasn't drawn more attention because three of the five crashes involved cargo planes, not passenger jets.

Losing Favor Eventually, airlines began turning their backs on the MD-11, for various reasons. They complained its initial range with a full load was 500 or so miles short of the expected 8,000-plus, because the engines didn't have the expected efficiency. MD-11s also were out of service more than comparable craft. Years of engine refinements and other upgrades never completely satisfied carriers. In phasing out the plane, both American and Delta cite economics rather than safety.

The toughest blow to the MD-11's public image came two years ago when the Swissair jet fell into the sea off Nova Scotia while circling around to make an emergency landing at Halifax. Regulators haven't yet made a final report on the crash, which killed 229 people, but a short-circuit is strongly suspected as the reason the jet was filling with smoke. Afterward, the FAA issued more than 80 safety directives mandating inspections and expensive repairs to MD-11s' electrical systems, insulation and engines.

There will be no more new MD-11s after the last one is completed any day now. Tom Melody, the chief Boeing investigator on MD-11 accidents -- and one of its original test pilots at McDonnell -- is frustrated that "such a good airplane got such a bad reputation." Every time a problem has cropped up, the manufacturer has fixed it, so that with some minor exceptions, "you can land this airplane just like you land a 747 or 767," Mr. Melody says. "We wouldn't know what else to change."

Still, the FAA has recently taken steps that appear to be indirect responses to one persistent MD-11 problem, the difficulty some pilots have in handling the plane. The agency is developing more-stringent criteria to evaluate aircraft stability, including ease and predictability of handling, before the next generation of planes gets the green light.

And the official in charge of aircraft certification, Thomas McSweeny, has indicated the FAA is rethinking how it monitors problems with existing aircraft. If any jetliner's "level of safety is not the level that was expected" when it was initially approved, Mr. McSweeny said recently, the FAA may re-evaluate its original design. He was talking in general about how the FAA looks at accident statistics, not particularly discussing the MD-11.

It isn't clear how those general comments apply to the MD-11.

The MD-11's poor reputation is a far cry from expectations a decade ago.

McDonnell Douglas developed its new jumbo jet inexpensively by basing it on the DC-10. At times during development, the St. Louis company faced cash-flow crunches because of troubles on its military contracts and declining market share in commercial jets. To build the MD-11, McDonnell lengthened the DC-10 fuselage, which moved the center of gravity backward.

The design reduced drag and promised a fuel-efficient plane. In part to compensate for the unorthodox design, including some unusually small movable parts on the tail, McDonnell relied heavily on computerized flight controls.

Some airlines bought into the high-tech vision. Delta Air Lines, American, Swissair, Korean Air, Japan Airlines and Alitalia bought MD-11s for long-haul routes, paying McDonnell as much as $130 million a copy. The plane became a staple of cargo operations, including FedEx Corp.'s. Today, about 60% of MD-11s in service carry passengers, about one-fifth of them at Delta and American, a unit of AMR Corp.

Both airlines are phasing them out over coming years. Most MD-11s are likely eventually to be flown by cargo carriers -- FedEx is taking American's -- or by passenger lines in developing countries. Safety experts are concerned that many planes will operate for decades under looser maintenance standards and less-demanding safety rules than the FAA imposes.

From the start, some pilots worried about sliding behind the controls of the distinctive-looking plane, with its third engine mounted high on the tail. They found its long fuselage tough to handle in crosswinds and were troubled by a tendency of the nose to pitch up at the critical moment of touchdown. Pilots say the MD-11's control column, or yoke, is more sensitive than those on other large aircraft, so that the normal amount of push and pull has more pronounced effect.

http://www.pprune.org/ubb/NonCGI/Forum3/HTML/001121.html
Author Topic:   MD 11 LSAS
Capt Sierra
PPRuNe Flight Deck Qualified

Posts: 16
Registered: Mar 2000

posted 05 August 2000 22:38     Click Here to See the Profile for Capt Sierra   Click Here to Email Capt Sierra     Edit/Delete Message
I flew the MD 11 for almost 6 years as a Captain, but I have a lot of questions regarding the LSAS and the lack of stability in the final ( A/P Off ). My trainning was at Long Beach, but nobody told me many things about the LSAS. Can somebody hep me?
Capt Sierra

IP: Logged

Prof2MDA
PPRuNe Flight Deck Qualified

Posts: 146
Registered: Feb 2000

posted 06 August 2000 00:33     Click Here to See the Profile for Prof2MDA   Click Here to Email Prof2MDA     Edit/Delete Message
Don't know if I can help until you ask the questions! I probably can. Also include what years you flew the -11 and what FCC load you were flying and whether the airplane was flown by a JAA certificated operator or U.S. or what?

IP: Logged

Capt Sierra
PPRuNe Flight Deck Qualified

Posts: 16
Registered: Mar 2000

posted 06 August 2000 12:01     Click Here to See the Profile for Capt Sierra   Click Here to Email Capt Sierra     Edit/Delete Message
Dear Prrof2MDA.
Tks for your help. I flew the MD 11 from 1992 to 1997 and we follow the FAA rules. My question regarding the LSAS is thet in the final with auto pilot OFF, the big bird in unstable, that is, you must fly it all times, it never maintain tha pitch stable. Before the MD, I flew the 767 for 5 years and the stability on final of the twin is nice. You simply trim it and you can fly almost hands off. That is my big concern about the flying characteristics of the MD. I'll check the update of the FMCS ( Honeywell ) and send an e-mail to you.
Tks again
Capt Sierra.

IP: Logged

Capt Sierra
PPRuNe Flight Deck Qualified

Posts: 16
Registered: Mar 2000

posted 06 August 2000 12:08     Click Here to See the Profile for Capt Sierra   Click Here to Email Capt Sierra     Edit/Delete Message
Prof2MDA
Is me again. Please check the article " How safe is the MD11?" at <http://www.airlinesafety.com>. This article and my personal experience in the aircraft is the leading point of my doubts.
Tks
Capt Sierra

IP: Logged

Don Elbert
PPRuNe Line Training

Posts: 2
Registered: Apr 2000

posted 06 August 2000 13:33     Click Here to See the Profile for Don Elbert     Edit/Delete Message
This answers a lot of questions I've had. After flying as a pax on the MD-11 a lot, I couldn't figure out why the approaches were like roller coaster rides, with every pax pale and bringing out rosaries. I read a couple books on aviation, followed these boards, trying to figure out what was the deal with these landings.

I've only been on Swissair MD-11's, and it feels like the pitch is being maintained with thrust, like one would in a Cessna.

IP: Logged

Prof2MDA
PPRuNe Flight Deck Qualified

Posts: 146
Registered: Feb 2000

posted 06 August 2000 15:32     Click Here to See the Profile for Prof2MDA   Click Here to Email Prof2MDA     Edit/Delete Message
I've read the articles at that web site, but that guy that wrote those is mostly mis-informed. Not to say that things couldn't be improved on the MD-11, and that is happening.

The LSAS increases pitch stability with pitch attitude hold and pitch rate damping. However, pitch rate damping currently is not active below approx 15,000'. It is active on FCC 908 load, which is being installed in our fleet right now, and recommended by NTSB to be installed in all MD-11s.

The 767 does not require it, nor does the DC-10 or any other non-FBW design. The MD-11 is really controlled by FBW, and is much more fuel efficient than those other types are, and like the 777 it requires artificial handling to make it fly more smoothly. The handling is a tradeoff for aerodynamic/fuel efficiency. I do not know why pitch rate damping was not included all the way to the ground in the first place, but have heard rumors relating to certain certification authorities who made them remove it. In any event, with pitch rate damping I expect the issue to be fixed.

One other thing. If you turn the autothrottles off on final the pitch really smooths out. What happens is that the airplane is fairly easy to overcontrol as it is now, and each throttle movement requires a slight pitch change. The autopilot has no problem with this. Additionally, with the autoflight on the airplane becomes full FBW, instead of having the flight controls moving just certain control panels and the rest of the panels following those due to the interconnections.

IP: Logged

747400CA
PPRuNe Line Training

Posts: 7
Registered: Jul 2000

posted 09 August 2000 19:25     Click Here to See the Profile for 747400CA   Click Here to Email 747400CA     Edit/Delete Message
LSAS as explained to me during MD11 factory training 1991 (with apologies for any technical inaccuracy conveyed):

"LSAS is a 'yaw damper' in the pitch axis intended to provide the requisite longtitudinal stability after the horizontal stabilizer shrank [for drag count] 40% from that of a DC-10"

"Even while hand flying, LSAS in effect keeps the pilot in 'CWS' as it attempts to provide stability in response to pitch excursions - both external and internal".

In 4+ years on the MD11, it seemed that LSAS rewarded a smooth pilot but penalized an average / mediocre / "having a bad day" fellow horribly by opposing every pitch input - particularly in descent and approach.

Disconnecting autothrottles did help, particularly in gusty conditions.

Nice to hear of the pitch damping change to the latest software load.

Hope this helps - Regards.

IP: Logged

Prof2MDA
PPRuNe Flight Deck Qualified

Posts: 146
Registered: Feb 2000

posted 10 August 2000 04:47     Click Here to See the Profile for Prof2MDA   Click Here to Email Prof2MDA     Edit/Delete Message
I don't know that the LSAS is what makes the aircraft unforgiving to bad technique. I would agree that the airplane is unforgiving of bad technique, but I believe that is due to the inherent lack of dynamic pitch stability due to the fact that LSAS is not providing that at lower altitudes where most hand-flying is done, i.e. below 15,000 feet, as it washes out below 16,500'.