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Increase Gross weight to 1560 for AA-1….has anyone installed the STC from Fletch Air for the 1560 weight increase? I have installed on my N5902L AA-1 the first STC from Ken Blackman for the 150 HP and 74DM6 Prop. Ken’s STC came with an increase in T/O weight to 1579 but landing remains at 1500 sad face. I bought the plates and brackets and STC from Fletchair and wanted to ask any chiseled veterans out there in Grumman land who may have taken on the project of installing the 1560 gross weight STC. It’s all about drop testing I think, but imagine installing the brackets on the main spar (fuel tanks) could be tricky…
I moved the battery to the rear cargo comparment bulkhead and removed the bulk of the interior and the vacuum system, installed dual G5’s. This reduced my weight 87 pounds and brought CG back to legal. Want the 1560 so my son can more easily take check rides with large size DPE’s LOL -
I have the Collier / Fletchair STCs on my AA-1B for both the 0-320 and GW increase. I installed them back in 1984. This gives a GW increase to 1600 on the B for both T/O and landing. Thinking back I thought the GW STC called out that it can only be applied when used along with the Collier Engine STC, calling out that STC #. So the question for you IA would be can you stack the Collier GW increase STC with Ken’s Engine STC.
For my AA-1 Yankee project (N5930L) I have Ken’s engine STC and plan to just go with that for the increase GW. I have a set of the main gear plates that I also got as I thought Ken’s STC also called for them, but it does not. Those plates are not light, and since I don’t need them I do not intent to install them.
On my -1B, I kept the battery on the firewall. That plane still has the stock alternator and starter. I have about 7 lbs of lead in the tail. I thought that preferable to putting the battery in a tough spot to work on. And the Collier STC called for a 35 amp battery back there in a mettle Piper battery box. That with the long #2 cable, I figure I saved weight keeping the current battery location and using ballast.
I hope to do the same on the Yankee, keep the battery on the firewall, use a Plane Power alternator and Skytek starter. The engine is at Lycon now. Fingers will be crossed when the plane goes on the scales the first time.
The gear brackets attaches to the center spar, there is no fuel there.Rich
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Thanks that is very helpful. You are correct. The STC under conditions and limitations says the compatibility of previously installed equipment….it also says SA2477SW must be accomplished prior to installation of SA4106SW.
So I might have bought something I can’t use. Not sure yet. Fletch Air sent the heavier plates and the STC paperwork, that was Juan. Then my mechanic looked at the plates and the gear hardware which was already installed and
correctly surmised the plates would not fit, the bigger plates are ostensibly what gives it the boost to 1560. Yes I will lose about 4 or 5 pounds (difference between already installed plates) and new ones, but to be legal for landing, if taking off at 1579# under Ken’s STC, we can’t land for an hour and a half. We burn 48 # per hour with the O 320 and electronic ignition.
If we had the 1560 weight that would reduce the time to only 19 pounds or about 15 to 20 minutes of burn. Feel like we have a Boeing and have to consider several different weights LOL!!
I can call David and ask, I am glad you responded, because I thought the gear attach points might be at a wet section of the spar. Now I know better, thank you!!
My mechanic before moved the battery for us, since CG was very critical. When I bought this, it had a 16 pound ballast in the tail OMG! With the vacuum system gone, the interior out, several non-essential items removed, wheel pants removed etc we got to a point with a useful load of 494 pounds. That is really amazing. BTW, these aircraft were certified (ours is 1969) with weight and balance that was pre-GAMA for AFM/POH standardized format on W&B. They weighed these early models without oil and that was called licensed empty weight. You will notice in the AFM of the earlier models in the weight and balance section the addition of oil and its arm and moment for calculating W&B along with fuel, occupants and baggage! We had ours re-weighed without oil as it should have been. Many owners and the A&P’s they hire to weigh their aircraft over-look this.
Have a great weekend, thanks again for the information.
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I have in my 1969 AA-1 serial #0202 the sky tec and 60 amp hartzell they help but not much. Getting rid of vacuum lines and pumps almost 11 pounds and from the forward section where you will be heavy. IMHO you will need to relocate the battery unless you want 16 pounds of lead in the tail. Ken did have an STC to relocate the battery. You will be at your limit on nose up trim upon landing. Also, remember the airplane was certified with licensed empty weight which DID NOT include oil. Again that oil sits forward and will add to the forward moment. Seems weird but that is what the manual shows in the weight and balance section and in the Airplane flying Handbook, they discuss the pre- 1974 GAMA non-standardizations that existed. After reading your post, I am not going to be able to install the plates as a condition is to have the Collier STC which Fletch bought installed. I have Ken’s which I think is not as good of an STC in that there are no provisions included in his STC for battery placement or for increased landing weight. Not to bash dearly departed Ken, but having the ability to shed weight, move battery and increase landing weight is important in a little plane with a big motor and propeller!
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Yes, I would talk to David about that. The gear leg brackets are different between the AA-1 and 1A compared to the 1B, and I knew it would require longer bolts to accommodate the plates. That was a question I had a few months ago if I needed the 1B brackets to be able to mount the plates.
I am not sure what made my -1B so special. I also owned an AA-1A at the time I was doing the conversion on the the -1B, and I noticed my -1B had a much more aft CG then the -1A. The only significant difference I remember is the ELT mounted in the tail on the B. But I think there is more to it then that, just not sure what. -
Thanks, you made me look closer at it, I regret spending the money on the STC for the 1560, buyer beware. I did not do my homework. And the STC says “For N5902L only” written on it. So I could really only sell the brackets, not the plates as the plates come with the STC paperwork. It’s a learning experience. Need any brackets? LOL!
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You might be right about the CG on the AA-1. After reviewing the CG data on the AA-1, it’s forward limit is about 1″ aft of where it is on the AA-1B for a given weight. This I can understand with the different airfoil, the true laminar airfoil center of lift is further aft. What I don’t understand is they maintained the same AA-1 forward limit on the AA-1A, then changed it with the -1B. This must have been to ease the certification of the new wing. The AA-1A is aerodynamically the same airplane as an AA-1B, but was FAA Blessed with a very small CG envelope.
I might be faced with (god for bid) moving the battery back. I am going to look at any other options first. I would put up with say around 10 lbs of led in the tail, but if it looks like it needs more, then I would reconsider. -
Yeah and I spoke to Ken Blackman on the phone and was perplexed that anyone would not be faced with being forced to re-locate the battery. He said the STC allowed for a ballast in the tail. I told him we were severely limited on payload with our Dallas Metroplex long range tanks. He said he didnt know too many AA-1 drivers with the big motor that gave much attention to gross weight numbers! Well I bought it for my son to build hours and to do check rides in, I wanted it to work on CG and fuel with him and a 180 pound DPE. We have done that, but it was a long road. Gutted interior, battery relocation and removal of the vacuum system. Goodbye wheel pants. It was sure nice to throw the 16 pound lead weight in the trash and get the numbers to work. The interior was kind of gross anyway. I found it had two layers of interior walls, someone had put blue panels over the original red. Mind boggling!
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It looks like going with the Skytec starter and Plane Power alternator will save 10 pounds off the nose, I figured this works out to about 4 lbs of ballast in the tail. If I did this on my AA-1B, I could remove over 1/2 of my current ballast.
Another option my IA has brought up is the Odyssey PMAed battery. It will save about 9 pounds over the Concorde. He does not think it is an issue to install under a 337.
When I can do the first weighing of the Yankee I will start making dissensions. I would still prefer to not move the battery, and will only do it as a last resort.
I like the idea of removing the vacuum system, but not quite ready to spring $4500 for a set of G5s. That would be down the road.
My AA-1B never had wheel pants. I had collected a complete set to install in it, but decided the weight was more then the benefit. I wound up selling them to Ken Blackman about 5 years ago. I am interested in the Vans RV wheel pants that Fletchair holds an STC for, they are lighter and cleaner looking I think. I might go that route for the AA-1, depending on cost.
Also over the last 35 years since installing the 0-320 I have thought about adding the aux tanks to my -1B. Again the extra weight kept me from doing it.
If I had installed them, I would have done Ken’s system. I learned to slow the plane down to about 125 mph and I get about the same range it did with the 0-235. I have many trips around the US in this plane. I have trust in the Sight Gauges. I would expect to even do better in the Yankee due to higher speeds and a higher compression engine.
I am building up the Yankee as my personal flyer. I hope to have a plane with more performance then my -1B. At some point down the road I will have to make a decision on which one to keep. If the Yankee turns out like I hope, I will be selling the -1B. But not until after August of 2021, I will have owned it 40 years then. -
Wow you have been in it for the long haul with 40 years of ownership under your belt! I checked into that battery set up too! Even called the company that manufactures it. Now it was about a year plus ago and they had not been able to get approval from the FAA. If you can put it in they said it needed a heavy metal container, so there goes the utility right down the drain, thanks FAA. If it was experimental no problem! We just flew tonight from KCXO to 60R (Navasota) pretty windy tonight. Plane runs like a champ we baby her and with the electronic ignition and good compression it gives us some confidence. Have to have it to fly at night! My day job is 737 captain for United. Flying that little plane we realize we are down to our last generator, last engine and that adds a little pucker factor to someone used to a Boeing. We run our 320 at 2350 RPM and lean it out with our EGT/CHT and Hoskins fuel flow and by ear. It burns right at 7 GPH or about 42 pounds per hour. That gives you just under three hours till empty not a lot of range. That is with the electronic ignition too, which saves us about a gallon per hour. I have a 1/4 thick canopy for my plane, I bought it because my mechanic said I should since the one we bought was not trimmed quite right. Then my favorite mechanic said baloney the material you have there is enough and it won’t crack. So if you need a perfect 1/4 thick AA-1 canopy I have one for sale. I have it in my house so it’s not been exposed to lots of heat. Still has the protective sticky plastic on it! Less than a year old. OK gotta run I fly tomorrow to MCO then up to EWR and down to RWS. Third day back to IAH and a Cancun turn and done. Take care fly safe!
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