VariEze Mandatory Ground Inspect for corrosion and limit flight operations before next flight.
Long-EZ and Defiant Mandatory Ground Inspect for corrosion per this newsletter before next flight.
IMPORTANT STRUCTURAL NOTICE VARIEZE WING SPAR AND WING ATTACH STRUCTURE
A VariEze wing center-section spar cap has failed. This compression cap totally failed just inboard of the right wing attach fitting. The failure appears to be caused by high flight loads; however, the failure was discovered on the ground and did not result in an accident. This is the first known failure of a VariEze fiberglass primary structural component.
Tests conducted at RAF have shown that the compression cap was joggled on installation and samples from the other wing show serious weakness. It is possible that other VariEzes also have weak spar caps and, thus, RAF is recommending that all VariEzes immediately be subjected to significant flight restrictions.
RAF is in the process of attempting to develop an acceptable spar cap repair procedure in order to allow VariEzes to operate safely. Due to the way the VariEze wing attach aluminum parts are jigged and installed during the wing fabrication process, it is not feasible to merely replace affected components. It may be necessary to modify the wing structure in a way that will not allow wing removal.
Following the discovery of this failed spar cap and during the disassembly the builder discovered very serious corrosion in the aluminum parts of the top right wing fitting. The corrosion would also have resulted in wing failure if it had not been discovered.
The corrosion problem and inspection requirements have been covered in directives in the Canard Pusher newsletter on six previous occasions: CP 53 Oct '87; CP 55 Apr '88 ; CP 66 Jan '91; CP 86 Oct '96; CP 87 Jan '97; and CP 107 Jan '02. (These notices are printed later in this bulletin).
In spite of these notices we continue to see occasional examples of severe corrosion, the extent of which is likely to cause wing failure.
Based on the data we have seen to date there is a high likelihood that an EZ will lose a wing resulting in a fatal accident unless builders ground their aircraft and carefully inspect them. Builders of experimental aircraft are, in general, careful to do inspections and check all newsletter notices. Those who operate, but did not build their aircraft are generally at a much greater risk since they often ignore notices or are not experienced at inspection and repair. If you have built an experimental but are no longer operating it, do take the responsibility to notify and assist the new owner so he can fly safely.
Details from the spar cap failure incident follow:
After discovery of the failed spar cap (a "loose feeling" when moving the wingtip) the aircraft was grounded.
During the teardown to find out what had happened, considerable corrosion was found in the top WA-2 aluminum plate. The owner of this aircraft promptly contacted RAF, and offered to send the corroded and failed pieces to us for our evaluation. He later also sent additional pieces of his center section spar box so we could conduct some structural tests.
We have carefully examined all of these materials and parts, and have also conducted compression tests on the unidirectional E-glass spar caps from both the left and right sides of this center section spar. The corrosion found in the WA-2, WA-2-2 plates and the WA-5 spacer from the top right side wing attach fitting, is inter-granular corrosion in the WA-2 plate particularly, and thus cause for concern for anyone operating a Varieze.
For now at least, we feel that this incident is comprised of two separate and different problems. The severe corrosion of the aluminum wing attach plates is one and the failure of the glass spar cap is the other, and there does not appear to be any connection between the two.
Such severe corrosion in this wing attach fitting, in a Varieze that has been flying for 20 years means that it is possible that many other VariEzes out there could also be affected. This particular Varieze was built in North Andover, Maine, and was based at and flown from the Lawrence, MA (KLWM) airport. It was purchased by Andreas Christou in June of 1992, and moved to the Waterbury/Oxford (KOXC) airport. It was subsequently moved to the Sky Acres (44N) airport in 1997. All of these locations are on or near the North East coast. It has been parked outside on the ramp in a marine environment all of its life except when brought home for the winter for maintenance.
This Varieze was built before the recommendation came out to Alodine all aluminum parts. For some reason not understood, only the right upper wing fitting was affected by this corrosion. The lower right, and both upper and lower left wing attach fittings on the center section spar are essentially corrosion free. In this case the owner had installed cover plates over the normally visible, wing attach aluminum plates. These consisted of thin aluminum covers that were fitted over the wing fittings, and held in place using silicone as an adhesive. This made it impossible to inspect the actual WA-2 wing attach plates during a normal pre-flight walk around. Had it been possible to easily look at the top surface of the WA-2 plates, there were indeed indications of corrosion at the inboard edges of this WA-2 plate that should have been noted during a pre-flight inspection.
If you own a Varieze which has had any kind of cover installed such that you can not closely inspect the normally visible WA-2 wing attach plates, remove them before next flight, and do not re-install them. It is possible that these covers actually allowed moisture to become trapped in the void under this cover, and exacerbated the corrosion problem.
Before next flight, remove both wings and carefully inspect the top of each wing attach fitting, the WA-2 aluminum plates on the center section spar box. Carefully check both left and right and top and bottom plates. Look for little gray lines indicating possible corrosion, extending from under the composite lay-up/micro fairing inboard of these fittings. Examine with special care between the plates and look closely at the visible face of the WA-5 spacer. See page 6-17 in Section 1 of the Varieze plans to be sure you completely understand this important paragraph.
In the case of the Varieze involved in this incident, the corrosion was obvious using the described inspection above. If you see any signs of corrosion, you must ground your aircraft, and conduct a much more thorough examination, which will include actually cutting into structure, and removing the WA-2 plates.
In the subject Varieze, the top right WA-2 plate was so severely corroded that the corrosion had worked its way completely through this 1/8' thick plate, reducing the physical qualities of this plate to the point that this alone would have caused a wing attach failure. The WA-2-2 plate and the WA-5 spacer also are heavily corroded, particularly in the area of the void between the "ears" or tabs of the WA-3 tongue, which is part of the wing fitting on the wing itself. See the top view on page 6-17, the WA-3 tongue and the WA-5 spacer, are outlined using a dashed line. Please report any findings of corrosion to Rutan Aircraft Factory , or by snail mail to RAF, 1654 Flightline, Mojave, CA 93501.
Center section glass spar cap failure
The failure of the actual unidirectional glass top spar cap, just inboard of the right WA-2 wing attach plate was likely caused by an in-flight overload, and occurred right at this location due in part to glass fibers that were not straight, and also what appears to be a rather poor quality laminate. We have carefully removed a section of the glass spar cap inboard from this fracture point, and upon close examination, have found what looks like a rather dry, resin-starved lay-up. We made up 8 test coupons, cutting up the spar cap inboard of this dry-looking local area, and we have failed each of these in compression using an Instron Lab testing machine. The average compression failures occurred at only 68% of the expected stress.
In addition to this test we also conducted a compression test of the left upper wing attach/spar cap. The left compression spar did not fail in flight, and on close inspection, there did not appear to be any damage to the spar cap. It is of course possible that there may have been some compression damage that was not detectable. There was no corrosion visible in the aluminum wing attach plates in this area nor in the bottom fittings of both wings. The section of spar cap immediately adjacent to the WA-2 aluminum plate, failed in this compression test, at a stress level of only 25% of the predicted maximum stress. This indicates a serious weakness, however the test method may have induced some side-loading of the cap.
This is extremely serious, because it seems likely that since this has occurred in this one example of a Varieze, that there may be other Variezes out there in the field that have similar weaknesses. There is no way, short of a load test to failure, to determine that any particular Varieze has a similar problem. Such a test would of course render the aircraft un-flyable, and even if tested to a lower "G" value, there is a good chance that undetectable damage would occur during such a test, making the subject aircraft unsafe to fly.
During the testing described above, all of the samples failed without the normal "cracking" sound we have come to expect. They simply failed in what seemed to be a "soft", soundless failure. Certainly not what we normally see when conducting compression tests on composite laminates.
We are worried that there may be more of these weaknesses out there. There is no easy way to determine if your particular Varieze has the same problem, and there is no simple fix for this problem. For these reasons RAF believes that all Variezes must be grounded upon receipt of this information, and a carefully conducted examination of the wing attach fittings must be completed before next flight. In addition, no Varieze should be flown to a load factor above 2.5 "G"s. Also, you must avoid flying in greater than light turbulence, and of course, do not fly over the 1110-lb gross weight limit.
RAF will be attempting to contact all known Varieze builders/fliers, through the RAF web site, Sport Aviation, the Canard Pusher, the Central States Newsletter, and all other sources available to us. We would also ask you as a Varieze owner, to pass this information on to any one you know of who is flying a Varieze.
DETAILED CORROSION INSPECTION Before next flight, all Variezes must under-go the following:
If your Varieze has any kind of cover installed such that you can not closely inspect the normally visible WA-2 wing attach plates, remove them and do not re-install them. It is possible that these covers can actually allow moisture to become trapped in the void under this cover, and actually cause a corrosion problem.
Open your Section 1 of the Varieze plans, and turn to page 6-17. Study the drawing of the Brock manufactured wing attach assembly, and keep this page handy so that you will clearly understand the following instructions.
Using a flashlight, closely inspect the visible part of each WA-2 aluminum plate on the top of the aircraft, and each of the WA-2-5 aluminum plates visible on the underside of the plane. Pay particular attention to the inboard edge of these aluminum plates. Look for little gray corroded lines extending from under the composite lay-up/micro fairing inboard of these fittings. Also look for any gap that may be building between the composite structure and these aluminum plates.
Now remove both wings, and place them on padded sawhorses such that you can easily inspect all areas of the aluminum wing attach fittings, on the wings as well as on the ends of the center section spar. Remove each aileron from the wings, and set them aside.
On the center section, use your flashlight to examine between the aluminum plates where the WA-3 tongue normally fits. Look for any signs of corrosion on the inner surfaces of these plates, as well as on the visible face of the WA-5 spacer.
On the wings conduct the same careful examination, paying particular attention to the inside edges of the "ears" of the WA-3 tongues, but look at every surface, on top and underneath the wings. You are looking for little "wiggly" gray lines of corrosion, or any pitting on any surface indicating corrosion.
Any indication of corrosion in any of these areas is cause to ground your Varieze, and to conduct a much more in depth examination. This may include actually cutting into structure to get a better look. Report any discovery of corrosion to RAF. raf@antelecom.net is the email address, or via snail mail, RAF, 1654 Flightline, Mojave, CA 93501
If you find absolutely no indication at all of any corrosion in your wing attach fittings, you may return your Varieze to flight status with the following limitation: Never exceed 2.5 "g" positive, or 1.5 "G" negative in flight. Install a placard in plain sight on the instrument panel, with these words clearly shown. Also change all reference to flight at more than 2.5 "G" in your ownerÕs manual, to read 2.5 "G" maximum allowable in-flight loads.
Varieze Ailerons Corrosion Inspection
There has been a report of corrosion of the A1 aluminum tube, in the inboard end of the ailerons on an older Varieze, necessitating replacement of this tube. Therefore you must check yours at this time.
Before re-installing your ailerons, carefully examine the hinge areas of both ailerons. Look for any paint cracking around the hinges, or any signs of swelling around the aluminum tube A1 that is floxed into the foam core under the A2 aluminum bracket. The inboard hinge is mounted to the A1 tube and A2 bracket and the outboard hinge is attached to the aileron using Avex or Cherry rivets. See page 13-4 of Section 1 (Second edition) for detailed cross section drawings. Remove some glass, inspect and repair the glass per plans repair procedures.
Long-EZ and Defiant Ailerons Corrosion Inspection
There has been a report of severe corrosion of the A10 aluminum tube floxed into the inboard end of the foam core of the Long-EZ ailerons. The hinges are mounted to the aileron using Avex or Cherry pop rivets. These rivets pass through the hinge, through the glass skin of the aileron, and through the A2 (or A5) brackets. See page 19-14 for detailed cross section drawings of these areas. If moisture is able to find its way into the A10 tube it is possible that this tube and perhaps even the A2 and A5 brackets could become corroded. The fix is to cut the bad sections out of the aileron, and replace them with new parts, using the standard repair criteria of lapping 1" per ply onto well sanded existing known to be good structure. Be certain to treat all aluminum parts with Alodine just prior to installing them. This surface preparation will prevent any re-occurrence of corrosion.
Since the Defiant aileron is essentially identical to the Long-EZ, please follow all of the above instructions.
CANARD PUSHER NEWSLETTER REPRINTS
October 1987 CP 53 Page 4
VARIEZE PLANS CHANGES- MAN-GND
Next 10 hours - carefully inspect wing attach fitting for inter-granular corrosion.
October 1987 CP 53 Page 7
CAUTION: CORROSION IN VARIEZE WING ATTACH FITTINGS
A VariEze which had spent most of its life outdoors in the eastern US, but significantly, not on the coast, was found to have severe intergranular corrosion in the top plates of the wing attach fittings as well as in the two aluminum tubes between the top and bottom plates. Very little evidence of this was visible upon casual inspection. However, when the UND wrap on each end of the centersection spar was lifted, the corrosion was rampant and this EZ builder said he would not have flown this airplane knowing how bad the corrosion was.
All VariEze owners should make a very careful inspection of the aluminum wing attach fittings, especially under the glass that laps onto the aluminum plates, particularly if there is evidence that the glass has peeled or delaminated from the wing attach plates, both on the wings and the centersection spar.
For new construction, all aluminum parts, including wing attach fittings, should be cleaned in Alumiprep 33 or metal prep #79 and then soaked in Alodine 1201 which is a visible (golden brown) moisture barrier, greatly increasing resistance to corrosion. This also acts as an excellent surface to bond epoxy or paint.
Do not anodize wing attach fittings since this finish, if not done exactly right, can cause embrittlement in the highly stressed wing attach parts.
Alodine is a common aluminum preparation and can be obtained from RAF-approved suppliers such as Aircraft Spruce or Wicks Aircraft.
April 1988 CP 55 page 8
VARIEZE MAN GND
Check wing attach fittings for corrosion. Remove both wings, clean and inspect the wing attach fittings on the wings and on the centersection spar. See this CP for a more detailed description.
April 1988 CP 55 page 5
Since we first reported the corrosion problem in VariEze main wing attach plates in CP53, page 7, we have heard from only two or three builder/fliers who had found signs of corrosion. Just this week, we received a letter from a VariEze owner/pilot who found corrosion in the WA-2-2 plate. He has spent a considerable amount of time and energy removing this plate, in fact, he said he almost resorted to using dynamite! He sent us the WA-2-2 plate, the lower plate of the top two plates mounted to the centersection spar. By far the toughest plate to remove and replace. This plate (see photo on page 11) has one of the worst cases of intergranular corrosion we have seen. It is absolutely not safe to fly and must be replaced. Unfortunately, this is probably going to be very difficult, and we honestly do not have any simple fix for this. Just removing the WA-2-2 plate could do serious damage to the centersection spar. The UND wrap around the end of the centersection spar may have to be cut and removed. The foam under the WA-2-2 plate must be dug out, the 8 AN525 (or AN509) screws must be removed (drilling them out may be the easiest method).
A replacement plate must be fabricated, duplicating exactly all of the holes in the plate. This is a difficult job and will require an expert machinist and a lot of patience. Brock will not be able to help you with this. Each case will have to e dealt with on an individual basis. The new piece should be alodined and then floxed and screwed back into place. If the UND wrap was damaged, it must be replaced, which requires cutting into the fuel tank (we did say it would be tough!).
This is major work, not anything that could not be done by a person who has built a VariEze, but very tedious, difficult work. And it must be done right. There is no short cut, no easy way. If you find more than simple white powder surface corrosion, stuff you can easily polish off with 320 grit sandpaper, you must ground your VariEze and replace the corroded parts.
A mandatory inspection is required before next flight for all VariEzes. Do not take this problem lightly, it could kill you and anyone who may be with you. Remove both wings. Clean all visible aluminum parts at the wing root and centersection spar. Look at the edges of all the WA plates on the centersection spar. Look for a thinner edge or a swollen appearance under the glass. Look in between these plates (where the WA-3 tongue slides in). A white powder appearance that can be completely removed and polished out with 320 grit is OK, but the plates should be very thoroughly cleaned and sprayed with zinc chromate. LPS or a good quality grease as used in marine applications should be generously applied everywhere before re-installing the wings. Check the WA-4 pins and the AN4 bolts and grease both thoroughly. Replace the AN4 bolts if they show any sign of corrosion.
New construction VariEzes, or anyone replacing wing attach fittings with new ones, should clean all aluminum parts with Alumiprep 33 or Metal Prep #79 then alodine them with Alodine 1201 which puts a tough, corrosion-resistant visible, golden finish on. We are reluctant to try alodining parts in place due to the acid etch (Alumiprep 33) possibly getting under the glass onto the aluminum.
When you inspect your VariEze, be very conscientious. Check very carefully, it is difficult to find, you may have to probe under the glass over the WA-2-2 plates. Look hard and long at it before you decide it is safe to fly.
The only good news about this is that where the epoxy was bonded to this WA-2-2 plate which we have, there is no corrosion. The surface of the metal is as new. Intergrandular corrosion is very common in airplanes that live near the ocean.
Sea planes are especially prone and require constant inspection and maintenance aimed at preventing just this problem. The salt in the air plus water from rain or condensation, plus heat and aluminum and presto!, you have a battery! Galvanic reaction and you have corrosion. Keep the aluminum parts clean, grease them often and you will have no problems. People who live far from the ocean may not see this problem but they must check for it just the same.
This problem is confined to the VariEze. The Long-EZ wing attachment is completely different and this same problem should not occur. Of course, all metal parts must be protected from corrosion - aluminum with alodine or zinc chromate, steel with zinc chromate (after cleaning in Metal Prep). Wing attach bolts and parts should be generously covered with a good grease in VariEzes and Long-EZs. Replace any rusty bolts and nuts.
January 1991 CP 66, page 3 ALERT!
Possible Corrosion in Elevator Torque Tubes in EZs
We have one report from a VariEze builder/flyer who lives and hangars his EZ in Ohio. He noticed small bumps rising up on the top of each elevator along the aluminum torque tube. He could depress these bumps a little with his finger. He has removed each elevator and cut the glass and foam away along the top of each elevator, exposing the aluminum torque tubes. He reports that he has found "severe corrosion pits where each bump was located." He says that this corrosion occurs only under the foam and glass. There is no corrosion at all on the exposed ends of the elevator torque tubes.
Pitch control is absolutely critical to safe flight. For this reason, any report such as this must be taken seriously. ALL EZ, Defiant and Solitaire flyers should inspect the leading edges, the tops and bottoms of both elevators for bumps such as we have described here, before the next flight. If any evidence of bumps or corrosion is found, ground the airplane and remove foam and glass locally. Inspect the aluminum tubing under a bright light. Please report any problems found to RAF as soon as possible.
Any builders who have not yet built the elevators should treat the aluminum tubing with Alodine before starting on the foam and glass elevators. Do not omit this step! Remember, the corrosion, if it exists, is not visible on the exposed part of the tubing. It is under the foam and glass and cannot be seen without removing the foam and glass. Do not remove foam and glass without evidence of bumps or swellings that may or may not be soft. Do let RAF know of any evidence of corrosion.
The above report came of Ohio where it is hot and humid in summer and cold and damp in winter. Anyone who lives where there is much humidity and/or near the coast should be especially concerned and should check the area called out before each flight.
We have checked all of the EZs at Mojave with no sign of any problems but that probably was to be expected, this being a desert with only a few inches of rainfall in a good year.
October 1996 CP 86 page 4
Corrosion Found in Brackets A Long-EZ pilot has reported finding moderate to severe corrosion in the elevator hinge brackets on his GU canard. He did not build this airplane, and the history of this airplane is not known, but it currently is based on the East Coast in a salt water environment and the corrosion was significant enough to cause this pilot to dig out all of the hinge brackets and replace them.
We have not found anything like this on any of our aircraft, but keep in mind all of the EZ types here in Mojave live in hangars and in a dry desert environment. We will continue to investigate this problem, and will report in future CPs. Every EZ and Defiant owner should make frequent careful inspections of these hinge brackets. Keep in mind that there was little or no evidence visible outside the canard. The corrosion took place inside the canard, where the bracket was floxed into place in the high density foam insert. Probably moisture was "wicked" up into the flox/high density foam and was trapped in close proximity to the 2024-T3 aluminum brackets.
What can be done to prevent such an occurrence? The best thing to do for these brackets, and all other aluminum parts, is to treat the bare aluminum with Alodine 1201, after pre-cleaning with Alumiprep 33, prior to installation. They should then be sealed in pure epoxy prior to bonding them into the canard.
January 1997 CP 87, page 9
Don Yoakam, Ft. Myers, Fla .- In the last newsletter you asked if anyone has much trouble with corrosion of the metal parts of their EZes. Just move to Florida and you will soon find out about such things. My VariEze sat under a flat metal shade with no walls. It is about seven miles form the Gulf. The hinge brackets started to corrode and I tried several things to stop it, but none worked. In the end I dug them out and replaced them with ones made of stainless steel. We would appreciate hearing from anyone who may find corrosion in this or any other area. Feedback from builder/flyers is extremely important and is our main source of information relating to safety.
I now have a Long EZ and made its brackets out of stainless. However the canopy hinges on it started to corrode and I had to cut up the hinges to get the canopy off. I have just a little nylon rope for a canopy stop and the little metal bracket that the rope is tied to will corrode where the rope goes through it. I just replace the bracket every year. I keep after the rudder and aileron hinges with WD-Forty and have had no trouble with them. The aircraft now has 770 hours on it and first flew in 1984. That is all the trouble that I have had with the air frame. Of course a little trouble with the engine, but that is another story.
It is a fine airplane.
January 2002 CP 107 page 8
Jonas-strutt Audrey - My EZ (ser. no. 21930) wing attachments are disintegrating, that is the aluminum is separating, that is flaking off. Have you heard of this happening? If so what was done, or can anything be done to stop this condition? Can the attachments be replaced or must I part my old bird?
Burt Rutan - This is a real tough one. As described in an early newsletter the aluminum components need corrosion protection for all but our dry desert environments. They are not easily replaced, since the units are jigged as a unit during construction. I have seen others resort to building new wings and center section to deal with wing attach corrosion. There may be a way to avoid this but RAF has never worked out or approved a repair procedure.
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