----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- Dear Mr. Caldwell,
I recently recieved a notice of a proposed AD on Ercoupes due to corrosion found on one airplane during inspection. I recognize that Univair Service Bulletin #31 covers this potential problem, and the means to check and prevent future corrosion problems. However, I am very surprised that apparently Univair did not publish the Service Bulletin to registered Ercoupe Owners. I have owned an Ercoupe since the mid 80's, and have previously recieved Service Bulletins on a regular basis..as they were issued from Univair. I understood the FAA regulations required a holder of a Certificate to notify registered owners of a new service bulletin. Is this correct? Did Univair mail noticces to all registered owners as (I thought) required? The Ercoupe Owners Club just published your letter on the Notice of Potential Airwothiness in their November 2001 issue., which I recieved just last week. This leaves little time for owners, mechanics,and inspectors to respond to the notice with a closing date of November 26th. Please consider extending the date for another 30 days. However, I will try to list several concerns that may be of help. 1. One commenter on the Ercoupe list stated he had talked to you by phone, and got the comment from you "Ercoupe Wings are falling off". I suspect you were mis-quoted. I hope so, because the FAA accident reports DO NOT SHOW this to be a true statement. ( At least the FAA accident reports I can access do not show such to be true.) It is said that the engineering data shows that the Ercoupe center Section is stronger than that of an early Bonanza. (I am not sure I can provide this data). 2. We have been experiencing corrosion in wing spars...but unusual in the web areas. Most of this corrosion in spars is of the type due to contaminated materials in the aluminum when built, Intergranular; not due to weather related and exposure to moisture. 3. As a borescope inspection found this named incident, then I agree an inspection should be required to insure safety. It is already required on every annual inspection, and as shown can easily be accomplished with a borescope. However some mechanics and Inspectors may not properly inspect every item. Even a new AD will not correct this personnel problem. 4. Until you recieve adaquet data from the field, this incident is just that. Many badly corroded aircraft are donated to Schools for their use when no longer economically repairable due to extensive corrosion. Generally these orphan airplanes have been left to the elements and not properly cared for. Recently an Ercoupe was listed on e-Bay, and an EOC member visitied the airplane for a visual inspection. The airplane was located on an airstrip close to the ocean, and tied down for many years. There were holes through out the fuselage due to sea water spray corrosion. Of course this was not mentioned on e-bay. Thanks to the EOC Member, our other members were not led to a mess...BUT, this type thing does not require an AD to correct. 5. I suspect the noted incident is a result of mice urine, or stopped up drainage holes, as it is described as exfoliation corrosion......surface corrosion, I understand. If this is the case, proper maintenance and observation of drainage holes would have prevented this problem on this aircraft, and does not require an AD to correct. On the other hand , were it intergranular corrosion as is showing up in some main spars, then an AD might be advisable - recognising that the original material may have been manufactured with included contamination. (the cause of intergranular corrosion). 6. I urge you and the FAA to, as I know you will do so, consider all the evidence you can gather before issuing a new AD on the Ercoupe. We do want safe airplanes; and I recognize this is your responsibility; along with the owner and mechanic - to insure the airplane remains safe. However, unnecessary maintenance and "overboard" regulation often only moves owners to abandon their airplanes, to ignore AD's they feel are necessary, or to fly unsafe airplanes due to "calling Wolf" too often. I hope this is not the case in this incident. 7. Many folks are concerned about owning aluminum structured aircraft - corrosion, corrosion, corrosion. BUT, one of the reasons we use Aluminum in the construction of aircraft is because of its properties to resist corrosion. As you know, bare aluminum quickly corrodes on the surface, creating an aluminum oxide coating that further resists corrosion. This protective coating is permanent protection, until someone decides to shine it off. Then without surface conversion protection the corrosion process again forms a dull passivity coating, protecting the underlying materials. True, acid rain, animal urine, etc, do break down this protective layer. So, it is advisable to coat the aluminum surface with conversions and coatings to resist this deteriorating effect. 8. Again, I have owned a 1946 Coupe ( an aluminum airplane) for almost 20 years. Luckily, I have not experienced these types of corrosion problems even though the airplane is stored out of doors, unprotected. However, I have observed many aluminum aircraft improperly stored, maintained and not cared for - or properly inspected - that have experienced severe corrosion. AD s would not have prevented this....only loving care by the owner. I don't think we can regulate this. I hope the above comments are not too long winded, and may be helpful in your effort to determine the true nature of this potential problem. We do want regulations and ADs that are really necessary to insure safe airplanes. I trust you will find this incident is an isolated incident, and does not require an AD. Sincerely, Harry L. Francis 2851 Sarver Road Ellliston, VA 24087 540-268-2307 phone 415 -D N-93530 S/N 853 ==^================================================================ This email was sent to: [EMAIL PROTECTED] EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Sid.bAhN69 Or send an email to: [EMAIL PROTECTED] T O P I C A -- Register now to manage your mail! http://www.topica.com/partner/tag02/register ==^================================================================
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