AVwebFlash - Volume 13, Number 47a

November 19, 2007

By The AVweb Editorial Staff
 
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Kermit Was Right: Being Green Isn't Easy back to top 
 

Avgas: Group Asks EPA To Get The Lead Out

The environmental group Friends of the Earth says Lead emissions from general aviation aircraft endanger public health and warrant regulation by the Environmental Protection Agency. Friends of the Earth is calling on the agency to either regulate or, if lacking present evidence, to investigate "the health and environmental impacts of lead emissions from general aviation aircraft." The EPA has responded with a Notice of Petition For Rulemaking and is asking for public comment by March 17, 2008. Friends of the Earth claims that 70 percent of general aviation aircraft can be accommodated with unleaded automobile gas and 82UL (a fuel that has not yet been produced for general aviation). The group contends that the remaining 30 percent "can potentially use" AGE85 (an ethanol based aviation fuel).

 
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Safety R&D — Sometimes Not So Safe ... back to top 
 

Airbus Ground Test Accident Shears Off Nose

Click for larger images

Five people were injured Thursday when Airbus suffered its first ground test accident. The event involved Airbus's second largest aircraft, a 359-seat A340-600, that "broke free" while testing its four engines (rated at 56,000 pounds of thrust, each) and crashed into a noise-reduction barrier at the Airbus facilities in Toulouse, France, according to news reports. The aircraft was set for delivery to Abu Dhabi-based Etihad Airways this coming week, but its cockpit was "sheared off" in the accident. The aircraft is likely a write-off. Etihad is waiting on six A340-600s from Airbus.

New Technology Makes Aircraft More Crash-Resistant

The Delft University of Technology in the Netherlands will demonstrate how the application of Fault Tolerant Control can be used to keep damaged aircraft flying and improve their chances of being successfully recovered. Fault Tolerant Control involves the creation and adaptation of on-board control systems to handle unanticipated in-flight emergencies and keep the shiny side up long enough to get the aircraft on the ground. "The key to this is to improve control techniques which enable the aircraft to continue to be controlled," the university said in a news release. "The implemented improvements are based on the analysis of flight data from aviation accidents by the NLR. This has led to improved interpretation of the (defective) condition of the aircraft." For the demonstration, the researchers have deconstructed the crash of an El Al flight near Amsterdam in 1992. The Boeing 747 freighter went down when both right engines fell off the wing while it was on final, killing four crew members and about 50 people on the ground. The data has been plugged into a simulator and the new control techniques applied to the rather remarkable set of circumstances faced by the flight crew. "Simulator experiments have shown that the new techniques make it easier for the pilot to land seriously-damaged aircraft safely," the university claims. The university also says there’s a lot of work to be done on the theories and it should be considered a long-term project.

 
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Pilots Effecting Change back to top 
 

Pilots' Legacy Aids Police Families

The families of two helicopter television journalists killed in a collision in Phoenix in July have donated much of the considerable public fund created in their memory to a group that helps the families of police officers killed in the line of duty. Pilot/reporter Scott Bowerbank and cameraman Jim Cox, of KVTK, died July 27 when their helicopter collided with a KNXV helicopter flown by Craig Smith, with videographer Rick Krolak on board. All four died. Bowerbank and Cox’s families have donated $500,000 to the TASER Foundation For Fallen Officers and asked that all subsequent donations be directed there. TASER Foundation spokesman Gerry Hills said it’s the largest single donation ever received and will be used to fund a permanent endowment to provide financial help to the families of fallen police officers in the U.S. and Canada. "We are overwhelmed by such generosity," said Hills. An average of 145 police officers are killed in the line of duty in Canada and the U.S. every year.

AOPA: Be Afraid Of User Fees ... And Act

"The FAA funding issue is far from resolved," AOPA President Phil Boyer warned in a release Thursday. President Bush is using public frustration over airline delays to push his administration's agenda of imposing a 263 percent increase in avgas taxes plus additional user fees, according to AOPA. For its part, AOPA is using the president's words to once again call on AOPA members "to contact their senators when the time is right." That time may come early next year. H.R. 2881, the FAA Reauthorization Act of 2007, has already passed the House of Representatives, but AOPA warns that Senate committees "are in disagreement over user fees versus taxes, airline tax breaks, and some other issues." Those issues will likely be back on the table in January, when AOPA says it will again be ready for the fight. AOPA says you should be, too.

 
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Helicopter Safety in the News back to top 
 

FAA Investigates Balloon/Police Helicopter Collision

A Honolulu department store could face the FAA’s wrath after a Honolulu Police Department helicopter tangled with the tethered balloon the store was using to advertise a sale. The HPD chopper was supporting ground units chasing a suspected thief last week when it clipped one of the lines holding the Savers Thrift Center’s promotion balloon over the store. The balloon is apparently a common sight in the area, according to KGMB News. The tether got caught in the tail rotor and whipped the fuselage but the pilot was able to land it safely and, after inspection, it was cleared for flight to a repair facility. FAA spokesman Ian Gregor says the store may have been violating FAA balloon rules. Gregor told the station that the maximum height a tethered balloon can fly is 500 feet AGL and it must be at least five miles from an airport. The store manager told the TV station his balloon was no more than 200 feet up, although the helicopter pilot claims he was 300 to 400 feet high when he hit the rope. Nevertheless, the rules also state that anyone who wants to put a tethered balloon more than 150 feet high has to notify the local FAA office and Gregor said there was no such notification.

Helicopter Herding To Continue Despite Crash

The Department of the Interior says it will continue using helicopters to herd wildlife in national parks despite an accident in October that destroyed a helicopter but only caused minor injuries to the pilot and the biologist on board. The NTSB says the Bell 206 snagged the top wire of a fence as the chopper was being used to coax wild horses into a corral. The aircraft went into a dynamic roll that the pilot was unable to correct and landed on its left side, destroying the rotor, ripping the transmission from its mounts and busting off the tail. The pilot had more than 35,000 flying hours, including 21,000 in the 206. The horses were being rounded up in Theodore Roosevelt National Park, near Medora, N.D., and were to be auctioned off. The crash ended the roundup and the auction, the first in four years, and the horses were set free.

 
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Good Vibes, Bad Karma and a Few Mixed Feelings back to top 
 

Pilots: Just A Happy Group Of Guys And Gals

Despite airline bankruptcies, the withering of cushy retirement plans and having to suffer the indignities of long security lines to get to work, pilots are a happy lot, according to the Nov. 26 issue of Time. In an article about job satisfaction, the magazine reports that 49 percent of professional pilots say they're "very happy" with their jobs, ranking them near the top on the job satisfaction spectrum. A lower percentage of police officers, physicians, lawyers, teachers and engineers say they're happy with their jobs. Pay may have something to do with it. Time reports the median pilot income as $141,090.

Airplane Noise Linked To High Blood Pressure

It may be music to the ears of some, but airplane noise may be hard on the heart. A Swedish study suggests that men who live near airports have a greater risk of developing high blood pressure than those who live in quieter neighborhoods. "It is thought that aircraft noise causes stress problems when it interferes with people's ability to think, relax or sleep, for example," study organizer Dr. Mats Rosenlund of the Karolinska Institute in Stockholm told Reuters Health. The study followed 2,000 men, who didn’t have high blood pressure, for 10 years and found that the 20 percent of study subjects who lived in the noisiest area were 19 percent more likely to develop it. The study took into account lifestyle factors like obesity, exercise and eating habits. Rosenlund cautioned that the study does not prove that airplane noise causes high blood pressure but he did say it was consistent with other studies that draw a link between blood pressure and noise.

Flight Delay Solutions Get Mixed Reaction

President Bush’s plans to ease congestion and reduce flight delays over the coming holidays were panned as too little, too late in some circles but embraced as a sign of hope in others. Bush announced that “the epidemic of flight delays” will be addressed with the opening of “Thanksgiving express lanes” through military operating areas on the East Coast through the five days surrounding Thanksgiving. That’s been done before for weather diversions, FAA spokeswoman Elizabeth Cory told The Chicago Tribune and it might help a bit. However, critics say Bush’s solutions are politically motivated and will have little practical benefit, especially if the weather turns sour. The National Air Traffic Controllers Association maintains that opening up airspace is futile if there aren’t enough controllers to manage it. It claims there are 7.5 percent fewer experienced controllers on the job this Thanksgiving than last and traffic is up 4 percent. "Until the FAA finds a way to keep its veteran controllers on staff to handle holiday traffic, and ALL traffic year-round, and train new hires, the system will continue to deteriorate," NATCA spokesman Doug Church said in a statement. Bush also said FAA staff are to stop all "non-essential work" so they can help keep traffic moving, but details on just who would do what where were scarce. Bush’s political foes wrote the initiatives off as the president’s attempt to appear to be doing something in the face of a looming holiday season of increased delays and mounting frustration from travelers.

On The Fly...

A Thai Air Force helicopter pilot was suspended for landing his aircraft in the jungle so he could pick wild mushrooms for his mother. Local villagers reported the incident after they found the abandoned aircraft…

The family of a pilot missing in B.C.’s rugged interior are asking for public help to find him. Ron Boychuk, 61, disappeared Oct. 23 on a flight from Revelstoke, in the Rocky Mountains, to Nanaimo on Vancouver Island. The official search has been called off…

The FAA is tweaking the airspace and procedures around New York to try and ease congestion over the Thanksgiving holiday. The results aren’t expected to be dramatic but officials say anything is better than nothing…

A near-collision between two regional airliners near Chicago last week resulted from a controller error, but that doesn’t mean control facilities are understaffed and the controllers overworked, says the FAA. The aircraft came within about 1.3 miles of each other at 25,000 feet when the TCAS in one of the planes sounded an alert.

 
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New on AVweb back to top 
 

CEO of the Cockpit #76: Flying Cars

If you put a parachute on a plane and a professional pilot in the left seat, haven't you got a limo?

Click here for the full story.

It was a nice, sunny day at home. A day off with great weather can be a rarity where I live and I intended to enjoy it to the full. My neighbor and fellow pilot, Chad, and I had one appointment to attend to before we headed out to play tennis. Apparently, there is such a thing as a free lunch and an aircraft manufacturer was about to provide us with one. We're talking top-of-the-line steak and cocktails at a top-of-the-line steak and cocktails place.

It was obvious whey they invited Chad. He is a rich lawyer who happens to own a Beechcraft Duke. Why they invited me remains a mystery. The company that was providing a $50 lunch said they only wanted us to sit through a 40-minute presentation about their bird. Then we would be free to play with their mock-up that was located in the parking lot and perhaps go for a demo flight later. I won't name the manufacturer here, but rest assured that this is an aircraft company so confident of its design that it attaches a parachute to each and every model it produces.

Why Would An Airplane Bail-Out On Itself?

I have always been a little skeptical of an airplane having its own parachute. I am probably wrong and old-fashioned in my discomfort; even Cessna Aircraft has recently announced that they will be attaching chutes to their single-engine line. It's just that, as an airline pilot, I've gotten used to the concept of bringing the airplane to the ground in a controlled method, not landing it like a Soyuz spacecraft re-entering the airspace over the former Soviet Union and slamming down onto the steppes below a canopy.

"If I have to use a parachute during an in-flight emergency," said Chad, "I want to have it on my back or butt and bail out like a man. John Wayne would never have a parachute on his plane. It would be like putting a trigger lock on his trusty 0.44 or putting an airbag on his horse."

The statistics that Nate, the salesperson, presented at the lunch were compelling. For some reason, people have gotten the idea into their heads that they should fly their light, single-engine aircraft through all sorts of weather at night. Their parachute system had saved some lives.

"This airplane can fly in very low and foggy conditions and has deicing systems and a thing called "WAAS" that can help you steer around bad weather," said Nate. "The parachute gives you an added margin of safety should something go wrong." He then showed a slide of their airplane enjoying a smooth ride above a solid undercast.

Lucky Chuck

I've been guilty of flying light singles in heavy rain at night and in 200-and-1/2 weather in the past, but now I don't really feel comfortable in nasty weather without about 300,000 pounds of Boeing 767 around me. I know it is a weakness on my part and I know that single-engine flight has come a long way since the early days, but Lucky Lindy wasn't called "lucky" for no reason. When Chuck crossed the big wet in his single-engine Ryan monoplane, the reliability of his motor probably crossed his mind more than once during that night.

We were halfway through the salad course before Chad noticed what we should have seen as obvious: Except for the salesperson giving the spiel, we were the only pilots there. This particular aircraft company had come to a marketing conclusion that every general aviation manufacturer should have arrived at years ago: The industry should not be selling to pilots, they should be selling to non-pilots!

The little-airplane makers should be basing their marketing efforts on proving that their aircraft isn't really an airplane so much as it is a luxury car. I'm not talking about the people who refurbish P-51s or build aerobatic aircraft, but let's face it: Most pilots can't afford to pony-up $600K for a single-engine ride but rich people can.

Wanted: Pilot-Heifers

What better way to "increase the herd" of pilots than to offer the dream of flight to your basic oral surgeon, trust-fund baby or tort lawyer? I know that light-sport aircraft (LSA) is another big trend and is considered a "gateway drug" by the manufacturers. They figure to trade people up from their LSAs to bigger iron at a later date. This particular company decided to go right for the people who already were wealthy enough to blow big money for a new airplane. They recognized it is unlikely that people who chip in for a tenth-share of an LSA will be stepping up to the half-million-dollar investment on a toy level of affluence any time soon.

That isn't to say that the LSA sector isn't a great thing and isn't doing a ton of business. At this year's Oshkosh alone, people lined up to write checks for the new Cessna SkyCatcher and the company doesn't even have a factory to build one in yet. Out of the 700+ people who wrote deposit checks that week, a few had bigger, more expensive airplanes, but they were fish that were already in the boat. This parachute-plane company was trying to re-stock the pond with a new crop of check-writing aircraft owners.

The CEO Considers A Career Change

Part of the deal with your new airplane is a full-time professional "eagle of the skies" of your very own ... for only $70 grand per year. That's right folks, I said $70 grand. To the people slurping martinis at the lunch and planning their next vacation to Aspen, this much money is one week's wine allowance; but to your basic, lowly, airline jock, that sounds like a lot of smackeroos to feed and water a single-engine corporate pilot. Heck, that is way more than airline pilots make a year for the first 10 to 15 years of their careers. I was beginning to wonder where I could sign up for one of these jobs until the show moved out into the parking lot after dessert to view and talk about the mock-up.

It was during this protracted conversation I had with the non-pilots that I thanked the aviation gods that for the past 28 years I had been protected from them by a locked cockpit door.

We were all standing around the mock-up and Rich Guy One said, "Dam'n Cletus, you can't fit my golf clubs in this thing!" Rich Guy Two, who was accompanied by Rich Lady One, said, "This is great! We can fly to the beach house at St. Simons any time we want. But how are we going to get the kids, the nanny and cook down there too?"

Rich Guy 3 summed it all up and confirmed the manufacturer's whole marketing plan when he said, "Yeah, I'll probably buy at least one of these things. I just came into 500 million bucks and need a fun plane to go along with the jet. I'll get one the same color as my new Lamborghini so they'll match."

Chad Wants To "Fly With His Boots On"

Nate worked his way over to me and wondered if I would ever be interested in owning a parachute-equipped, single-engine plane with my very own personal pilot to fly me to 100-dollar hamburger joints. I think my answer disappointed him when I told him that I am probably just being old-fashioned about this, but I want my airplane to be an airplane, not a car. I am personally sick to the teeth of cars. I am tired of dealing with cars, insuring cars, hitting other cars, paying to park cars, and filling cars with gas. When I fly, I want to fly, not drive.

Chad added, "Yeah, we want to feel the wind in our hair, the bugs in our teeth and a firm, rigid stick in our hands!" Obviously, Chad had enjoyed one cocktail too many, but in his own, marginally homo-erotic way, he echoed my sentiments exactly.

I hope the company in question sells a million new cars ... err, airplanes ... and that none of them needs to literally bail out on themselves. But as flashy as they are with their TV screens and whatnot, I'll take a steam-gauged, sputtering tail dragger that has adverse yaw out the wazoo any day over a glorified Toyota with wings.

But, then again, they weren't selling to me in the first place.



Want to read more from AVweb's CEO of the Cockpit? Check out the rest of his columns.

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Dry Vacuum Pumps

It is possible to increase the service life of your dry pump as well as have an idea of pump condition?

Click here to read this maintenance article.

The modern dry vacuum pump -- when it works -- is economical ($200 to $400), low-weight (under three pounds) and capable of high-output operation. The dry pump displaced its traditional competition (venturis and oil-lubricated "wet" pumps) in a matter of only a few years during the late 1960s and early 1970s.

The Achilles heel of the dry pump is -- as the FAA said in a 1987 letter to the NTSB -- that "pumps fail catastrophically, without warning, and there is no degradation of performance obvious to the pilot to warn him of imminent failure." Pump failures are not new stuff; what's changed is the magnitude of the media sensationalism surrounding a crash, especially with a senator on board.

On the Inside

Both Airborne (now out of the vacuum pump business, although theirs are the majority of the installed base of dry pumps) and Sigma Tec pumps utilize carbon-graphite rotor construction, with carbon vanes riding loose in the rotor slots. In normal operation, the vanes are thrown against the pump housing by centrifugal force, rising and falling on the elliptical walls and compressing the air trapped in vaned compartments.

Airborne units came in "CW" (clockwise) and "CC" (counterclockwise) models, and for longer life, the proper direction must be observed on installation. In either case -- Sigma or Airborne -- the vanes run dry on aluminum-housing walls. The constant, gradual, wearing away of the graphite is the only lubrication the pump gets. Hence the term "dry pump."

Dry pumps can be used to suck air (vacuum) or blow air (positive pressure), depending on which side you hook the plumbing to. When dry pumps are used to provide pressure (as in de-ice boot systems), in-line filters must be employed to remove carbon dust from the system.

Both Sigma Tec and Airborne pumps have a standard, spline-drive mounting for use on Lycoming or Continental accessory cases. Also, both makers incorporate frangible drive couplings designed to shear in the event of rotor lockup, thus sparing the engine accessory gears of possible damage.

The pump makers differ in their approach to drive-coupling design. Sigma's coupling transmits torque straight to the rotor along a thin quill-shaft (which has since been changed to a speedometer-type cable in the so-called "dash three" pump models). Airborne transmits drive torque to the rotor via a coupling sandwiching shear pins between a nylon torque plate and an upper torque plate, with the rotor spinning on three finger-spools, which "grab into" the rotor.

The Sigma Tec pump drive is "more frangible" than Airborne's nylon torque-plate drive. The Sigma is designed to fail at 100 inch-pounds of torque, whereas it takes 250 inch-pounds to snap an Airborne drive.

That said, even experts can have a tough time pinpointing the primary causes of a given pump failure.

A Complex of Causes

What causes pumps to fail? The use of carbon graphite as a structural as well as a lubricating material certainly seems intrinsic to the problem. Ironically, it's carbon graphite's unique qualities that make current "self-lubed" pump designs possible in the first place.

In our research (which included talking to pump manufacturers as well as mechanics, owners and overhaulers), we identified 10 things that could cause a dry pump to self-destruct:

  1. Solvent Contamination: Oil or oil vapor rapidly contaminates carbon graphite, turning the lubricating powder at the rubbing surface into sludge. Oil from the engine can enter the pump via several routes: a bad pump-mounting gasket, oil blown rearward from the crankcase breather, or drawn into the pump by its own suction.

    Additionally, entry into the pump of degreasing solvent (the type sprayed on the engine for routine inspections) can cause failures unless exceptional care is taken. Varsol can enter a pump through its exhaust tube or drive seals. This is something to watch for during any engine spray-down.

  2. Foreign Object Ingestion: Carbon graphite is fragile. A small sliver of rubber hose (liberated by wiggling the plumbing during pump installation) -- or even the carbon bits left in the lines by a previous pump -- can cause immediate failure.

    Generally, this type of failure occurs shortly after installation of a new pump. Pump manufacturers lay the blame for a large percentage of warranty claims to this cause. (A filter change is usually required for warranty coverage to be in effect after installing a new pump.)

    There is concern that particles small enough to pass through filters can mix with the lubricating powder at the rubbing surfaces of the vane and rotor, increasing the wear rate and leading to early pump failure. Even cigarette smoke is bad for the pump -- yours and your engine.

  3. Drive Misalignment: One of the more controversial (with manufacturers) aspects of the pump-life problem is a parallel misalignment of spline-drive gears caused by "engine drive gears not being where Continental says they are." Efforts to accommodate misalignment continue.
  4. Heat and Altitude Stress: The heat of compression developed in a dry pump operating at or near full output is conceptually similar to a turbocharger. The higher you fly, the harder the pump works. Internal pump temperatures can easily exceed 200 degrees F.

    Cooling is often poor, in part because of low humidity at high altitude and because aircraft designers don't always expose the pump to ram air.

  5. Over-Speed: Exceeding engine red line can trash a dry pump. Most pumps begin to provide usable suction (or pressure) around 1,500 rpm and provide optimal life at engine rpm below 2,000. (Not surprisingly, this is the speed chosen by designers of electrically powered backup pump systems.)

    The maximum continuous operating speed of Airborne pumps is 4,000 rpm (rotor shaft); for Sigma it's 4,200 rpm. Lycoming pump pads generally turn 1.3 times crankshaft speed. Continental pump pads turn 1.5 to 1.545 times crank speed. This equates to a Continental engine exceeding 2,588 rpm for Airborne or 2,700 rpm for Sigma.

    Combine high rpm with high demand (as in a Continental-powered Cessna P210 with de-ice boots flying at 20,000 feet), and you can begin to see why some operators experience so many problems with pumps. Add in a prop over-speed incident to the scenario and you are pushing the pump where it was not designed to operate -- for long.

  6. Rapid Acceleration: Rapid engine acceleration (on a go-around, for example) can apparently put unusual loads on the rotor and vanes, which may be why test-stand pumps often run trouble-free for many hundreds of hours, while operators in the field continue to rack up failures.
  7. Reverse Rotation: As mentioned earlier, Airborne pumps come in clockwise (CW) and counterclockwise (CC) flavors. The profile of the elliptical rotor bore is not symmetrical in an Airborne pump; also, the rotor slots are cut at an angle.

    Attention to instructions can eliminate incorrect installation of pumps. But avoiding occasional engine "kickback" on start-up (or shutdown) is not such an easy matter. If vane/ slot clearances have opened up, one kickback may be all that's needed to jam a rotor and trash a pump.

  8. Shock and Awe: The FAA's Service Difficulty Reports (SDR) file abounds with examples of "fresh out of the box" pump failures where just spinning the drive shaft by hand locked up the rotor. Assuming that the manufacturers exercise quality control, what could be the cause? One likely cause is transit "ship-shock," which can jar vanes enough to chip a corner (or cause other mischief).

    Of course, pumps respond poorly to having their housings squeezed in a vise, which many installers do while installing fittings. The makers have express warnings not to do this, but installers do it anyway.

    Float plane operators (who suffer a relatively high incidence of shock-related avionics and panel problems) have reported replacing vacuum pumps every 50 to 200 hours, on average -- further evidence that shock and vibration can have a destructive effect on pumps.

  9. Pump Lugging: A recent focus on pump failures in Cessna 210 wing boots has underscored that de-ice boots place a heavy burden on vacuum pumps -- ultimately detracting from reliability. Whether the erosion of reliability is due to the higher average pump loads or to other factors is not clear.

    The FAA has received SDRs describing sticking de-ice boot valves in some aircraft. Ordinarily, pneumatic de-ice boots cycle on and off, alternately inflating and deflating, at the behest of a small timer and solenoid-actuated de-ice boot flow valve.

    If either the timer or the valve hangs up in the "inflate" position, however, the vacuum pump can quickly lug and overheat. Until recently, the loss of a vacuum pump in this manner meant not only the loss of boot action, but gyro instruments as well.

  10. Normal Wear: Dry pumps inevitably wear out and if it is left in service long enough, any dry pump is eventually going to stop working. The question is, how long should a pump last?

    According to overhaulers' figures, under the best of circumstances, smaller (211-type) dry pumps are unlikely to operate reliably much over 600 hours, as the vanes will have worn to the point where they are likely to cock and jam.

    The pressure regulator valve (note the safety-wired head) is easily visible in late-model Bonanzas. The area at the base of the valve should be checked visually for excess carbon at each preflight. Rapid carbon buildup is indicative of pump distress.

    The so-called "boot pumps" (high-capacity Airbornes) are unlikely, in most applications, to last more than 300 to 400 hours. Of course, there are always exceptions.

In short, then, the modern dry pump, by virtue of its design and construction, is acutely sensitive to almost everything in its normal environment: heat, oil, solvents, dirt, water, vibration, mechanical stress and (some would say) the moon and tides.

Even under the best of circumstances -- with a new (gyros only) pump installed by experts, with cleaned lines and new filters -- you still cannot expect much more than five years of normal flying before your pump is a real candidate for failure. The only thing certain is that it will fail. You just can't say when.

Detecting Imminent Failure

What if your pump is on the verge of giving out? Is there a way to tell? Do you have to wait until the DG dies to learn that your vacuum pump has pumped its last breath?

On every preflight (if your cowl is openable), you should get into the habit of visually inspecting your vacuum pump and the pressure relief valve or exhaust tube. Look for oil at the base of the flange (indicating a bad gasket) or tiny bits of stripped nylon in the coupling area (which is open for view -- although you must look closely). Bits of nylon are an indication that the coupling is nearing failure.

In a pressure-type system, give the relief valve (in the firewall area) a visual once-over periodically. Look for carbon buildup (i.e., black soot) indicating possible rotor/vane distress. By checking at set intervals, you can get an idea of the normal soot buildup produced by your pump. Abnormal buildups will then be easy to detect.

In the cockpit, learn to include the suction gauge in your normal visual scan. In a dry-pump system, any rapid fluctuation of the gauge (no matter how intermittent) is a definite warning signal that something is amiss. See that your system is properly adjusted to give the correct readings at 1,500 rpm or above. (Most regulators don't begin to regulate until 1,500 rpm.)

Dual vacuum-pump installations have received a lot of attention, what with Cessna's experiences with the 210 series. Unfortunately, not every small-plane engine has an extra pad available for a standby pump. While the engine manufacturers have developed T-drive adapters for some applications, the drives are not widely "retrofittable." Still, if you want a standby vacuum pump in your system (and you don't want to trade up to a twin), there are ways to do it.

Pump Replace Checklist

Replacing a vacuum pump need not be a major hassle, if you follow a rational sequence of procedures.

  1. Troubleshoot Cause(s) of Last Pump Failure:

    • Booted aircraft: Check for normal de-ice timer operation. The timer should inflate boots for six seconds. (This is somewhat variable in pressure-dependent de-ice systems, but should not exceed 15 seconds for any one cycle). Boots should be pressure bleed-down checked for leaks using an Airborne 343 Test Kit.
    • Inflatable Door Seals: Check that the system inflates and holds pressure without recycling (no leaks).
    • Pneumatic Autopilots: Check autopilot regulators, servos and filters per manufacturer's specifications.
    • Other systems: Check pneumatic camera doors, avionics cooling, etc., per aircraft service manual.
  2. Replace All System Filters: Failure to change filters may void new-pump warranties. Pump inlet filters (pressure systems) and garters (suction) should be replaced once a year or every 100 hours. Central gyro filters should be replaced once a year or every 500 hours (ditto for auxiliary in-line filters).

  3. Verify Replacement Pump: Do not merely replace the existing pump with an identical part number. Consult the parts catalog or pump maker's application list. Also, if using an Airborne pump, conduct a rotation check: Remove the old pump and manually rotate propeller in normal direction while the drive pad gear is observed. (Observe proper safety precautions when turning propeller.) If the drive gear rotates clockwise, a "CW" pump should be specified. If counterclockwise, order a "CC" pump.

  4. Remove Old Pump and Gasket: Your old pump (even if damaged) has salvage value. Do not reuse old gaskets. New pumps should be mounted on the new gaskets that accompany them.

  5. Remove Fittings From Old Pump: Discard stripped or damaged fittings, or fittings with rounded wrench flats, etc. Thoroughly clean and dry serviceable new fittings before using them.

  6. Install Fittings In New Pump: Here, it is permissible to clamp the new pump in a vise at the base flange only, never at the center housing. Spray clean fittings with silicone lube and allow to dry before screwing them in by hand.

    Do not use Teflon tape, pipe dope or unapproved thread lubes. Tighten fittings one-and-a-half turns maximum, using a box wrench. Align fittings for plumbing connections in the aircraft.

  7. Check Drive Pad For Oil: The pad should be dry, with no oil leaking out. Replace the pad seal if necessary.

  8. Install New Pump: Be sure to lay the gasket in place first, then install the pump. If you drop the pump, discard it. (Likewise, if the pump shows obvious signs of damage, exchange it for another one.) Replace all locking devices. Cinch all four mounting nuts alternately to 50 inch-pounds minimum, 70 inch-pounds maximum.

  9. Install Hoses: Inspect hoses inside and out for contamination, condition, etc., and replace questionable hoses. (Replace brittle or aged hoses to avoid separation of inner layers of hose, which can break loose during handling and be ingested by the pump, leading to premature failure.)

    In a pressure system that has experienced pump failure, be sure to blow out all lines with compressed air from the panel side, to get remaining bits of carbon. Make sure hoses are connected to the proper fittings (do not swap inlet/outlet hoses by mistake). Use only specified fittings, not pipe fittings.

  10. Check Pressure/Suction Regulation: Run the engine to 1,500 rpm and check that the suction gauge is reading in the green (or per manual specs).

Airborne specifies a life limit of six years for nylon drive couplings. Factory kits are available for replacing couplings: Kit No. 350 for 211/212 series pumps, No. 352 for 440-series pumps.

In short, don't sit and wait for a failure, and be proactive.



More aircraft repair and prevention articles are available in AVweb's Maintenance Index. And for monthly articles about aircraft maintenance, subscribe to AVweb's sister publication, Light Plane Maintenance.

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AVweb's Monday Podcast: Unearthing the Maid of Harlech

File Size 12.1 MB / Running Time 13:15

Podcast Index | How to Listen | Subscribe Via RSS

As you may have read in Thursday's AVwebFlash, the sands of time have buried an intact P-38 for more than 60 years since it was abandoned on a Welsh beach. Now named the Maid of Harlech (for a town near the beach), the Second World War fighter will soon be recovered and restored to original condition, as was another P-38 well known to warbird and air show buffs as Glacier Girl. And in an interesting twist of fate, it turns out the Welsh aircraft and Glacier Girl probably left the factory within days of each other and were both part of Operation Bolero, the U.S. Army Air Force's first major mission to help the war in Europe. AVweb's Mike Blakeney talked with TIGHAR's Ric Gillespie about the Maid of Marlech's history and her future.

Click here to listen. (12.1 MB, 13:15)

 
New Product Announcement — OxyArm Aviator Headset-Mounted Cannula
NEW!!! OxyArm Aviator Nasal Cannula mounts directly on virtually all aviation headsets to provide continuous oxygen flow with minimal contact while flying. Its unique design removes the hassle of wearing an oxygen cannula during flight. Its presence is virtually unrecognizable. Visit Aeromedix.com to purchase this product today!
 
Readers Chime In back to top 
 

AVmail: Nov. 19, 2007

Reader mail this week about UFOs, WWII history, flight without airline delays and more.

Click here to read this week's letters to the editor.

Did Your Battery Die? Tell Us About It

Our sister publication, Aviation Consumer, will soon publish an in-depth report on aircraft batteries. As part of that report, the magazine would like to hear about your experiences with aircraft batteries -- good, bad or otherwise.

To take part in our online survey, click here.

AVweb's Newstips Address ...

Our best stories start with you. If you've heard something that 130,000 pilots might want to know about, tell us. Submit news tips via email to newstips@avweb.com. You're a part of our team ... often, the best part.

 
Wishes Do Come True!
Ever wish you could fly every approach like it was sunny and VFR?
Click here.

Happy Flying,
True Flight
(866) 443-3342
 
Your Favorite FBOs back to top 
 

FBO of the Week: Antrim County Airport (KACB at Bellaire, MI)

Nominate an FBO | Rules | Tips | Questions | Winning FBOs

AVweb's "FBO of the Week" ribbon goes to Antrim County Airport at KACB in Bellaire, Michigan.

AVweb reader Stan Prevost flies into KACB several times a year, and he tells us it's always a pleasant experience, accompanied by a warm welcome. Here's how Stan was greeted on a recent arrival:

As we disembarked the airplane, airport manager John Strehl met us at the airplane with two plastic bags, greeted us by name, and told us to help ourselves to tomatoes growing on vines they had planted around the terminal.

Fresh tomatoes! Can't top that!

Keep those nominations coming. For complete contest rules, click here.

AVweb is actively seeking out the best FBOs in the country and another one, submitted by you, will be spotlighted here next Monday!

 
Attention, Piper Owners and Pilots!
Join the fastest-growing and best association for Piper Flyers — the Piper Flyer Association (PFA), since 2004 providing same-day parts locating, faster answers to technical questions, an informative monthly magazine, online forums, national and regional events, an annual gathering, seminars, member discounts, and more for only $40 yearly. The PFA is located in the Blue Hangar on the Waupaca Municipal Airport (PCZ) in Waupaca, Wisconsin, 35 nm NW of Oshkosh. For more information, visit PiperFlyer.org.
 
A Little Adrenaline to Start Your Day back to top 
 

Video of the Week: Motorcycle Jumping an Airplane

Recommend a Video | VOTW Archive

Thrills and chills never fail to rouse our Monday-morning "Video of the Week" audience, so here you go — a motorcycle jumping an airplane:


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Try disabling ad blockers and refreshing this page.
If that doesn't work, click here to download the video directly.

'Nuff said!

Don't forget to send us links to any interesting videos you find out there. If you're impressed by it, there's a good chance other AVweb readers will be too. And if we use a video you recommend on AVweb, we'll send out an official AVweb baseball cap as a "thank you."

 
Find Your Next Aircraft on ASO!
When you search for aircraft on ASO, you get the most complete picture of the market available anywhere. View thousands of listings with detailed specs and photos or use ASO's advanced search tools to quickly find your next aircraft. Best of all, know that every ad is current and no time is wasted on stale listings. If you're ready for your next aircraft, it's ready for you — on ASO. Visit ASO today!
 
The Lighter Side of Flight back to top 
 

Short Final

Overheard in IFR Magazine's 'On the Air' Section
Overheard in IFR Magazine's "On the Air"

During a recent departure from Essex County Airport in Caldwell, New Jersey, the tower controller must have been frazzled with intensive student training in the pattern:

Tower:
Bonanza Seven Zero Mike Romeo, contact New York departure and have a good flight.

Bonanza:
To departure. Bonanza Zero Mike Romeo.

Have a nice day.

Tower:
It's too late for that.

Jack Meagher
Southern Shores, North Carolina

 
New Gift Ideas Have Been Added to AVweb's Holiday Marketplace
When purchasing gifts for family, friends, and flying buddies, go to AVweb's Holiday Marketplace. AVweb is the perfect place to find perfect gifts for pilots and aviation enthusiasts. And for yourself — forward the link to your family and friends as a hint as to what you want! It's easy online, with AVweb!
 
More AVweb for Your Inbox back to top 
 

AVwebBiz: AVweb's Business Aviation Newsletter

HAVE YOU SIGNED UP yet for AVweb's NO-COST weekly business aviation newsletter, AVwebBiz? Reporting on breaking news, Business AVflash focuses on the companies, the products and the industry leaders that make headlines in the business aviation industry. Business AVflash is a must read. Sign up today at http://www.avweb.com/profile/.

 
Names Behind the News back to top 
 

Meet the AVwebFlash Team

AVwebFlash is a weekly summary of the latest news, articles, products, features, and events featured on AVweb, the internet's aviation magazine and news service.

The AVwebFlash team is:

Publisher
Timothy Cole

Editorial Director, Aviation Publications
Paul Bertorelli

Editor-in-Chief
Russ Niles

Contributing Editors
Mary Grady
Glenn Pew

Features Editor
Kevin Lane-Cummings

Click here to send a letter to the editor. (Please let us know if your letter is not intended for publication.)

Comments or questions about the news should be sent here.

Have a product or service to advertise on AVweb? A question on marketing? Send it to AVweb's sales team.

If you're having trouble reading this newsletter in its HTML-rich format (or if you'd prefer a lighter, simpler format for your PDA or handheld device), there's also a text-only version of AVwebFlash. For complete instructions on making the switch, click here.

Aviate. Navigate. Communicate.