Is There A Grumman Guru In The House?

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Scott_M

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Scott_M
A friend of mine thinks he has found a Grumman AA-1B nearby for $20k. It looks to have minimal radios and no ADS-B. I have just started looking at the Grumman Pilots Association web page and the Grumman Owners & Pilots Association web page. He wants me to look at it in a day or two. I need someone very familiar with the type to give some me info about what will give me the most bang for the buck time wise during a walk around and look inside. I've got an A&P, but all of my experience is Cessna, a bit of Piper, and even less looking at Beech Dutchess.

One of the GPA videos on YouTube concerned an aircraft with very questionable spar problems and some undocumented repairs. I'm not doing a pre-purchase inspection by any means. I'm leaning toward recommending he only purchase after he finds an Grumman experienced A&P nearby who will verify the spars are in good shape. Is pulling the wings off during a pre-purchase overkill? Neither of us have access to a hangar. It sounds like his money is burning a hole in his pocket. The price seems about 50% of what few AA-1s I found the classifieds.
 
I flight instruct in an AA5 Traveler & have time in AA-1Bs. Since Grummans are bonded instead of riveted there are some issues with the bonding agent (read glue). Make sure there are no areas where the metal appears to be separating. The AA-1 airplanes are quite sporty to fly.
 
I own an AA-1A and bought it at about that price. It's a dirt simple plane. The engine is no different than any other Lycoming.

It has a free castering nose wheel which isn't maintenance heavy. There are 2 sight classes to check fuel, they sometimes leak. But it's a really easy plane to take care of.
 
Scott_M said:
I'm not doing a pre-purchase inspection by any means. I'm leaning toward recommending he only purchase after he finds an Grumman experienced A&P nearby who will verify the spars are in good shape. Is pulling the wings off during a pre-purchase overkill?
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I have an AA5B, but I believe that the wing assembly of the AA5's is similar for the AA1 types. You don't need to pull the wings to check for spar corrosion. The area where corrosion can be a big problem is on the tubular carry through spar which is mounted through the fuselage and extends about a foot or two from the sides. The tubular wing spar of each wing slides over the outer portion of the carry through spar and held in place with shoulder bolts. The landing gear is bolted to the rear of the carry through spar near the fuselage. The area of corrosion concern is on the top of the carry through spar between the outside of the fuselage, in front of the landing gear attach bracket, and ending at the edge of the wing spar. There is an access cover below that area (on the AA5's it is covering the fuel sump tank) and inspection is done by feel of the top of the spar. You can do much of it using a flashlight and angled mirror, but can't usually see to the rear portion of the top near the landing gear bracket. So it is best to wipe the top of the spar clean of dirt and feel for raised areas characteristic of intergranular corrosion.

Call John Sjaardema at Excel Air Services (http://www.excelairservices.com/) in Indiana. They're about 260 nm from Bowling Green Ky. I guess that he might be willing to send out an A&P for the prebuy. More likely he may know of someone closer for the job.

Good luck and enjoy.
 
My mechanic/IA at M02-DIckson Municipal has a lot of experience with the AA-1and 5 series. Only about 50 miles from KBWG. Call Liberty Aviation at M02 and ask for Jeff.
 
My knowledge is AA5 specific and I am not sure how much applies to AA1 but I suspect a lot of it.

Nose gear torsion bar is a weak spot on these planes. It is mounted across the firewall laterally (Kinda like a garage door spring).
Make sure that has been looked at and appears to be in good shape. They crack and then you get a collapse and prop strike. That happened on my AA5

There is a shoulder bolt AD on the carry through spar. Make sure that has been addressed.
I believe it is every 100 or 500 hours (I don't recall, just check the logs for the shoulder bolt AD and it will tell you). They need to be inspected. I believe they can be replaced and the AD goes away.

Find out if the AA1 has the new AD for the elevator delamination. It is brand new on the AA5s but I don't know if it affects the AA1s as well. These planes are all made from the same parts (-ish)
This one is not a big deal. If it needs to be done, I believe they add a rivet to the elevator skin.

Check for a history of tank leaks / repairs. These planes wing tanks will leak at some point. It is better for you if it was recent because it means it has been recently repaired and you will get to fly it for a few years before they start leaking again. (I am only kind of kidding here) They are susceptible to leaks so look for blue streaks on the bottom of the wing.

Check the shape of the baffling under the engine. Grumman's are rumored (but I have NEVER experienced it) to have cooling issues during the climb. Just make sure the baffling looks like it is in good shape and makes a good seal when the cowl is closed.

Check the quality of the piano hinge running along the top of the cowl. In its past if someone has left the cowl open and walked away, the wind will grab it and you will see (usually near the front) portions of the hinge housing are broken. It starts to crack / tear a little and a stop drill will prevent it from being an issue (This happened on mine)

Examine the canopy seal. There are 2 type's 1. Rubber meets rubber 2. Rubber fits into indention in the metal canopy threshold. You just want to make sure there is a good seal when the canopy is closed so it doesn't get too much water when washing it or if it is out in a storm.

Run the flaps up and down a few times. These flap motors fail from time to time (~$400 parts and labor to replace)

If all that stuff checks out and your A&P says the engine is in good shape, you are probably good to go.

Really the biggest thing is the nose gear where it mounts to the firewall. Everything else I mentioned are just the things I encountered in 4 years of AA5 ownership.
You can do some research on the serial numbers with the purple glue but my understanding is that is a non issue. Most have been addressed and there were never any incidents related to it. It is just internet Grumman lore that people like to talk about.

They are very good simple planes that don't require a ton of maintenance to keep flying.
They are incredibly fun and tend to be conversation starters on the ramp as they are a touch less common than Piper and Cessna.

Happy to answer any other questions or if you see specific things, you can call me (I AM NOT AN A&P) and I will give you my 2 cents (I AM NOT AN A&P)
Happy to look at any photos and give you my personal thoughts on them (I AM NOT AN A&P)

Good Luck!
 
I would like to jump in here ask about delamination. Does anyone know about a kit to repair delamination on the wing inboard spar? My bird has been waiting for this mystical kit for a few months now. My understanding of this issue is that a delam is repaired with rivets and sealant. Am I missing something?
 
Rich Holt said:
I would like to jump in here ask about delamination. Does anyone know about a kit to repair delamination on the wing inboard spar? My bird has been waiting for this mystical kit for a few months now. My understanding of this issue is that a delam is repaired with rivets and sealant. Am I missing something?
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I am guessing you're looking for service kit SK-125A which is cited in the Service Bulletins (and by reference any accompanying ADs) for repair of delamination. All it is is a set of instructions along with specifications for standard adhesive and rivets to be used. You can read a copy here: http://www.grummanpilotsassociation.com/wp-content/uploads/2015/01/SK-125A.pdf. Fletchair or Trueflight may have assembled kits to sell as a package, but it isn't required and the parts should be familiar to any A&P.

Is your shop telling you that it needs to be purchased and installed as a kit which is unavailable? If so, it would probably be worth your while to have them show you where it says that the parts must be purchased as part of a kit. If they can't, then maybe you can convince them to reconsider their position.
 
bkspero said:
I am guessing you're looking for service kit SK-125A which is cited in the Service Bulletins (and by reference any accompanying ADs) for repair of delamination. All it is is a set of instructions along with specifications for standard adhesive and rivets to be used. You can read a copy here: http://www.grummanpilotsassociation.com/wp-content/uploads/2015/01/SK-125A.pdf. Fletchair or Trueflight may have assembled kits to sell as a package, but it isn't required and the parts should be familiar to any A&P.

Is your shop telling you that it needs to be purchased and installed as a kit which is unavailable? If so, it would probably be worth your while to have them show you where it says that the parts must be purchased as part of a kit. If they can't, then maybe you can convince them to reconsider their position.
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I got a response from Fletchair yesterday afternoon that cleared up the confusion. I think Trueflight might be in the process of making kits, and that is where the A&P was ordering the kit from. Because of the location (inboard rib), fuel tank sealant and rivets are what I have been advised to use.
 
Glad you were able to help your shop sort this out.
 
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