Sunday, January 27, 2019

Airworthiness Maintenance Inspection Notes, A-1231 Curtiss-Wright

Back before the FAA existed, aviation in the USA was under the authority of the Department of Commerce's Civil Aeronautic Administration (also called the CAA).

In those days, much information was published in the interest of safety. Unfortunately, these documents are not readily available today.   Similar to today's Airworthiness Directives (AD's) were publications known as Airworthiness Bulletins or Airworthiness Maintenance Bulletins and were considered mandatory safety items.  Other CAA documents similar to today's Special Airworthiness Information Bulletins (SAIB's) were Airworthiness Maintenance Inspection Notes (AMIN).  These documents include safety related inspection items that should be required at annual inspection.  These are generally considered to be mandatory as well, but this is not verified. The AMIN's are aircraft model specific. 

We recently obtained a copy of document no. A-1231, Airworthiness Maintenance Inspection Notes for Curtiss-Wright Aircraft, dated July 7, 1941.  Covered in this document are annual inspection requirements for Travel Air biplanes and monoplanes (including CW Travel Air), Curtiss Robin, CW Jr., CW Sedan, and CW Condor.  CAP has taken the time to reproduce the four pages because they were hardly legible.  While we claim no responsibility for the technical content of these documents, we wanted to make this information available here for historical information to restorers, operators, and enthusiasts of the grand old flying machines.

Thanks to our very good friend and Curtiss Robin restorer, Lane Tufts, for providing copies of the original document.

Maintenance Bulletin No. 4 dated  December 27, 1938 - Curtiss-Wright Travel Air shock absorbers.  This one is mentioned by SPECIAL NOTE 12 in the above AMIN.


I am pretty sure this one was provided by Darrell Starr.

Call for Papers
CAP is looking for more of these old CAA documents and we intend to use this blog as a collection center for such information.  If any of our readers run across these old CAA documents, please send them to us and we will make these hard-to-find documents available here.

Saturday, December 15, 2018

STC SA1-210, Explained

I get many calls about the options available when doing engine upgrades on the Taylorcraft BC-Series airplanes under STC # SA1-210 (formerly known as the Gilberti STC).  It usually takes a pretty long phone call to go through all of it.  So I thought maybe it would be helpful to share some of the main points here.  If you are seriously considering the purchase of upgrade paperwork, I recommend that you read through this post, and then study our latest catalog.  This should help you get a bit up to speed on the configuration choices you have.  Write down your questions and then give me a call and we'll figure out the best package for your Taylorcraft.
I'll start off with some background history and this should help you understand how this STC has evolved and maybe it will explain a bit about how the FAA approvals are structured. 

2016 Keith & Joann Walker from Charleston IL
BC12-D with STC SA1-210 Configuration A

ORIGINAL STC 1958 - Jack Gilberti

Configuration A incorporates a C85-8 engine with the original (short) engine mount and the resulting configuration is equivalent to the factory TC A-696 model BC12D-85.  This retains original cowl/baffle/engine control cables/exhaust/ etc.  The fuel system has to be updated to have at least one wing tank and the fuel lines have to be verified at least 3/8 inch size.  This configuration has no electrical system.  It has the option to install some simple wing fitting modifications that allow maximum weight to upgrade from 1200 to 1280 pounds. Eligible propellers are the same as the TC A-696 model BC12D-85.

Configuration B incorporates a C85-12 engine with a replacement (long) engine mount and the resulting configuration is equivalent to the factory TC A-696 model BC12D-4-85.  The "4" means that the engine mount and cowling are extended longer by about 4 inches. Originally it was expected that the starter and generator would be the old style (heavy) Delco brand.  So that's the reason for the mount extension.   This configuration requires conversion to a larger baggage compartment and added electrical system with battery mounted about 24 inches aft of the seat back.  This offset's the CG change due to the extended engione mount. The fuel mods are required same as config A.  Cowling requires modification, a different exhaust is required, longer control cables are required.  The same max. weight of 1280 pounds applies if optional wing mods are done.Eligible propellers are the same as the TC A-696 model BC12D-4-85.
If you are considering this option (or any long mount option), I always recommend that you try to find an airplane already modified or a model 19 or F19 and go for a flight.  You will discover that the handling characteristics are different from what you may already know as the nimble B-series Taylorcraft.  To some this may be desirable. To some, it can be a surprising disappointment after going through all the work to do this mod. It's hard to describe this difference, but just imagine that your rudder authority is just a bit slower in reaction time.  Not in a bad way, just different. 


Configuration B was revised to declare the resulting configuration the same as TC 1A9 model 19.  This configuration is physically exactly the same as the prior described Configuration B (BC12D-4-85) in every way, except it was approved to operate at a maximum weight of 1500 pounds (if optional wing mods are done) - equivalent to the factory model 19 per TC 1A9 (under CAR 3 regulations).  As such it also became a "Flight Manual Required" airplane and no longer a "placard only" airplane.  All of the same fuel/cowl/exhaust/baggage/etc mods apply as aforementioned Configuration B.  Eligible propellers are the same as the TC 1A9 model 19.
By the STC wording, you essentially have the option under Configuration B to go with 1280 or 1500 pounds maximum weight.  The former keeps the airplane within the LSA weight limit.  The latter takes the airplane over the LSA limit.


Certified Aeronautical Products took over the management of the STC in 2010.  We have expanded the options beyond those approved in the STC, made possible through major alterations approved by a DER.  We call these STC deviations. These major alterations do not require additional STC but are incorporated under FAA form 337.  Rather than mention of them all here, please look at the catalog.  For example, a DER can approve certain non-standard propellers. Another example.... we offer DER approved deviation paperwork to substitute a C85-12 engine on Configuration A.  This makes it possible to have an electrical system (with the short engine mount) when modern lightweight starter and alternators are used... because we've determined that they fit.  It's a tight fit, though.  You'll find you might have to de-mount the engine to get your starter on and off.  But its not that hard to do.  So the DER approved deviations have opened the door to many additional configuration options for these modified Taylorcrafts.  Again, most are listed in our catalog.

Previously, I mentioned different exhaust.  Well, when you mount an alternator to the back of a C85-12 it will interfere with the cross-over tube on the original B-series exhaust.  Something has to be done.  If you want to fabricate your own, we can provide the Gilberti drawing for the model 19 style that extends the cross-over pipe farther aft.  The same exhanst configuration was done at the factory for the BC12D-4-85, 19, and F19 models.  Another more popular option nowadays is to convert to the Luscombe style split headers or Cessna 150 Hanlon Wilson style exhaust. We can provide DER approved paperwork for either of these or others, like Aeronca and more.

OTHER STC SA1-210 Deviation work

Our DER has approved some de-rated installations of C90 or O-200A engine (de-rated by limiting RPM to that for 85 hp).
Through DER and FAA FSDO/ACO coordination, we have also supported a few deviations to substitute an O-200A engine rated at 100 hp. This is equivalent to TC 1A9 model F19.  We had to do an analysis of a specific engine mount design, so a new mount is required (or you can order an F19 mount from Univair).

There are a lot of options.  Study our catalog and then give us a call with your questions.  We will gladly help you tailor your Taylorcraft with approved paperwork. 

Wednesday, June 13, 2018


We have received our latest prices for Taylorcraft Hydraulic Brake Kit from Grove Aircraft and our other suppliers.  Call us today to order yours.

Thursday, May 11, 2017

C85 Stroker - Which Prop Can I Use?

This issue has been a source of dilemma or misunderstanding for some.   I get a lot of questions on this.

Legally you must use the same propeller as a C85 and adhere to the same RPM limits as a stock C85 because the C85 stroker STC does not change the Certified engine rating.  

On paper, it is still a C85.  

I am not aware of any FAA approved power curve for the STC modified stroker configuration. When requesting such from Don's Dream Machines or Aircraft Specialties (the STC holders) I have been turned away but was told that "this engine is much more powerful than a stock C85".  I've even been told just how much power the engine produces on the dyno. 

Of course we all understand that because of the physics of engine performance regarding displacement theory (RPM/bore/stroke) more power will be produced. Don't get me wrong.  I love the guys at DDM and ASSI, but I must ask: What good is it to know the engine makes 108 hp on the test stand if you have no legal authority to operate it that way?  My issue as a DER is that without a certified power chart, there is no legal avenue to approve any propeller that might maximize the performance of this engine configuration. The approved data to go there has never been developed as far as I can tell. 

In my opinion, the FAA and STC Applicants did us all a dis-service by not requiring an official engine calibration test to re-rate the modified configuration. I am sure the reason this wasn't done is because doing so would have required the STC applicant to run 150 hour endurance test followed by 150 hour durability test to prove all parts out to the higher rating. I get that this is a money issue. But the flying public deserves to at least understand the realities they face. 

So we (the industry) are left with 2 choices. 

1.  Legally run the same propeller as a stock C85, not knowing exactly how much power you have, but at least assured you have equal or better performance than the stock C85 and have the comfort of staying legal. 

- or- 

2. Illegally running another propeller that optimizes the capability of the engine. Climb and cruise fast not having (Approved) assurance that the engine parts are going to survive to TBO. Be mindful that if you choose to operate this way, the STC holders, prop makers, and engine overhaulers are not likely to warranty an engine or propeller with apparent fatigue issues. Beyond this, I know that insurance companies and defense attorneys use expert witnesses who can tell when they see evidence of over-stressed and prematurely fatigued engine parts. All I am saying is... choose wisely. 

I believe there are many folks out there running illegal configurations, without knowing it... or without an understanding of the issues. I hope this article helps some of you out. 

Do I think the stroker engine is a good thing?  Well I do. It seems to be a most efficient engine. I would just appreciate having the legal avenue to use it to its full potential. The saving grace here is that these little 4-banger Continentals seem to be made of long-lasting bulletproof parts. And generally they're used on small-very forgiving airplanes affectionately thought of by many as just "barely" capable of killing you. 

Final thought:  Do you think Continental Motors never thought of this configuration?

Saturday, July 2, 2016

FAA-TSO Power Socket Receptacle Box


Certified Aeronautical Products, LLC is proud to announce that we have completed the development of our new  Power Socket Dual-Receptacle Box.  Available in 12VDC or 28 VDC with FAA-TSO approved parts or Experimental parts.

  • Two separate receptacles per box - power for up to two (2) devices
  • Mates with standard cigarette lighter style adapter plug.
  • Overall dimensions 2.5" x 2.7" x 5.8" 
  • Durable Box construction from 2024-T3 Aluminum Sheet 0.040 thick.  
  • Pre-wired with 14 ga. aircraft wire MIL-W-22759-14-9.  (24 inch wire pigtail leads)
  • Recommended for use with two 15 Amp Circuit Breakers
  • Overall Weight: 9.5 ounces (including wire leads) 

This power socket dual-receptacle box is perfect for portable GPS systems, Cell Phone Chargers, Laptop Power Supplies, or anything you would plug into your car during a road trip.
  • Power Sockets by Lone Star Aviation Corp.  -  FAA-TSO-C71 Approved
  • Box assembly drawing FAA-DER approved for major alteration
  • Box assembly parts fabrication/quality subject to acceptance as Owner Produced Parts 
  • Box assembly parts PMA pending   

Ideal for General Aviation, Vintage aircraft, and Home-builts.
  • May be permanently mounted (customer must supply fasteners)  -   or  -  
  • May be temporarily mounted using hook and loop fabric fasteners (Velcro).

Standard Prices:

FAA-TSO Approved p/n 1161-45:   $  325.00
EXPERIMENTAL p/n 1161-45X:   $  199.00

plus shipping

specify 12 or 28 V

Introductory Sale Prices:

FAA-TSO Approved p/n 1161-45:   $  279.00
EXPERIMENTAL p/n 1161-45X:   $  169.00

plus shipping

specify 12 or 28 V

Until August 15, 2016

TO ORDER: CALL (254) 715-4773


DOCUMENTATION: click here for Lone Star Data

Thursday, June 23, 2016

VINTAGE WHEELS - How long will they last?

On April 23, 2016, My beloved Taylorcraft turned 70 years old.  Looking at the log books, It has accumulated 4,335 hours total time since new. For its entire life, the airplane has resided with various owners in Central Texas.  I have known of the airplane since the mid 1970's.  And so I am aware that most of the years since, it has been continually hangared.... about half that time in an insulated hangar, about 20% of that time tied down outside on an airport tarmac, and the other 30% of the time in a sheltered open air T-hangar.

I am not absolutely certain that the Shinn wheels are the original ones on my plane, but I have no reason to believe that the wheels on this airplane have ever been changed.... until last annual.  I have no idea how many landings they have had over all these years, but it must be a lot.  And hard landings.... groundloops.... well I am responsible for quite a few since this is the airplane in which I first learned tailwheel flying as a teenager.

So how old are your wheels? Do you know their history?  How many hours or, more importantly, how  many landings have they had?  How close have you been looking at them on your annual inspections?  Or, does your I.A. look at them closely?  How about the wheel bearings?  Have you ever found them worn or with signs they've been chattering or grinding?  And when you replaced those hardened steel bearing races, how did you get them out of their aluminum (or magnesium) boss?  Thinking back, I went a lot of years as a rather inexperienced mechanic in training and it is entirely possible, although I don't recall for sure, that I might have used screwdrivers, hammers, and other less-than-proper tools for the job.

What I am getting at is this.  Our old vintage wheels have likely had a pretty rough life.  If it weren't bad enough that they have probably been subject to poor and corrosive environmental conditions, hard landings, blown tires, side loads (groundloops), numerous cycles of bearing spin-up loads; it is entirely possible that they've been abused by green-mechanics or well-meaning owners.  And that's not to mention they're all subject the natural process of Age-Hardening that occurs over time to cause aluminum (or magnesium) to become brittle with age.

I heard about a Luscombe awhile back that rolled up due to a wheel problem.  Also an Aeronca owned by one of my friends had a wheel let go.  I don't know the cause of the Luscombe issue, but my friend says his wheel had some casting flaws (voids) from which cracks propagated until the eventual failure which occurred on the runway (on landing roll-out I think).  He's had plenty of damage occur and he's lucky he was not hurt himself.

The following are photos of the Left wheel from my Taylorcraft.  Upon removal to re-pack the bearings at my last owner-assisted annual, my good friend and I.A. called me over to take a look.  Lo and behold!!!! He'd found a crack.  The photos show the story.


So to get my plane back into the air, another Taylorcraft owner (My good Friend Greg House) came to my rescue with a used Shinn wheel that he had bought at a fly/flea market or ebay or somewhere.  I received it in the "as removed" condition with absolutely no record of what it came off of, let alone how many hours/landings it had.

So I cleaned 'er up via media blast and set out to inspect, alodine treat, and zinc chromate primer paint the two halves.   Once I got to inspecting it, guess what!?!?!  Well it had some imperfections of its own.  I am unsure whether I am seeing corrosion or casting anomalies.  I am more leaning toward declaring it casting voids.  But either way, these imperfections are cause for concern.  Let us know what you think.

 Have you inspected your Vintage Wheels lately?

Finally - It needs to be said.... This is not just a Taylorcraft / Shinn Wheel issue.  It goes for Aeroncas, Luscombes, Wacos, and all.  Here is a photo recently shared on the Luscombe Facebook page.  The submitter says it is a Cleveland DMB wheel, which is found on many light airplanes.  Don't wait for an AD.  We highly recommend you check your wheels with increasing frequency as time goes on.

Be safe!!! 

And...... Keep the Antiques Flying!