New AD Applies to all Husky Years and Models Effective 9/1/20

David

David

Active Member
What I want to know is why I, nor anybody I know that has a Husky, was not notified by the FAA about this new AD. Notification by the FAA for ADs and other urgent matters is the sole purpose of the FAA requiring us, under penalty of oppressive laws, to keep our addresses and location of the aircraft current.

Have any of you been notified by the FAA of this AD?
David
 
David

David

Active Member
Here is the background on why this AD occurred.

The FAA received three field reports from Aviat Aircraft Inc. of complete failure of the rear horizontal stabilizer inboard support tube. The first incident, discovered during a scheduled inspection, occurred in 2005, and the second incident, discovered while the airplane was being re-skinned, occurred in 2009. The third incident was discovered during a pre-flight inspection in 2012 and included a complete failure of the forward horizontal stabilizer inboard support assembly. Failure analysis of both parts from the 2012 incident concluded they failed due to fatigue. In addition to these complete failures of the rear support tube, the FAA received two field reports from Aviat Aircraft Inc. of cracks in the rear support tube, discovered during inspections, in 2005 and 2013. Aviat Aircraft Inc. subsequently issued Service Bulletin No. 28, Revision A, dated April 2, 2015, which requires a one-time inspection of the rear stabilizer inboard support tube in response to the multiple reports of failures and cracks.

In addition to the 2012 incident, which involved a failure of both supports, the FAA received two other field reports from Aviat Aircraft Inc. of complete failure of the forward horizontal stabilizer inboard support assembly, one in 2000 and one in 2019. In the first incident, the failure occurred during ground handling after flight. In the second incident the failure was discovered while the aircraft was being placed in a hanger.

Failure of either the forward or rear support transfers loads to the other support, increasing the likelihood that both could fail. This condition, if not addressed, could result in stabilizer departure and loss of airplane control.
David
 
David

David

Active Member
Thought you all might find this interesting too!

All of this info + more at: https://www.federalregister.gov/doc...4/airworthiness-directives-aviat-aircraft-inc

Differences Between This AD and the Service Information
The service information only applies to certain serial numbers of the airplane models identified in this AD, while this AD applies to all serial numbers of Aviat Aircraft Inc. Model A-1, A-1A, A-1B, A-1C-180, and A-1C-200 airplanes. The service information only requires inspecting the rear stabilizer support tube, while this AD requires inspecting the forward stabilizer support assembly in addition to the rear stabilizer support tube. The service information only requires a one-time inspection, while this AD requires both initial and repetitive inspections.

Costs of Compliance
The FAA estimates that this AD affects 941 airplanes of U.S. registry.

The FAA estimates the following costs to comply with this AD:

Estimated Costs

Action Labor cost Parts cost Cost per product Cost on U.S. operators
Inspect forward horizontal stabilizer inboard support assembly for cracks 1 work-hour × $85.00 per hour = $85.00 $25.00 $110.00 $103,510.00
Inspect rear horizontal stabilizer inboard support tube weld joints for corrosion and damage 0.5 work-hour × $85.00 per hour = $42.50 0.00 42.50 39,992.50
The FAA estimates the following costs to do any necessary repairs or replacements that would be required based on the results of the inspection. The FAA has no way of determining the number of airplanes that might need these replacements:

On-Condition Costs

Action Labor cost Parts cost Cost per product
Replace forward horizontal stabilizer support tube 2 work-hours × $85.00 per hour = $170.00 $296.00 $466.00
Repair rear horizontal stabilizer support tube weld joints and install new support tube insert 4.5 work-hours × $85.00 per hour = $382.50 163.00 545.50
Report if cracks are found 0.5 work-hour × $85.00 per hour = $42.50 0.00 42.50
 
jhickstx

jhickstx

Member
David said:
What I want to know is why I, nor anybody I know that has a Husky, was not notified by the FAA about this new AD. Notification by the FAA for ADs and other urgent matters is the sole purpose of the FAA requiring us, under penalty of oppressive laws, to keep our addresses and location of the aircraft current.

Have any of you been notified by the FAA of this AD?
David
Click to expand...

Yes, I received an email from the FAA Regulatory site on 8/17/20. I was signed up to receive any ADs, SAIBs or other info for the following:

Engine|Lycoming Engines|O-360-A1P
Propeller|MT-Propeller Entwicklung GmbH|MTV-9-B
Small Airplane|Aviat Aircraft Inc|A-1C-180
--------------
https://public.govdelivery.com/accounts/USFAARGL/subscriber/new?preferences=true#tab1
 
S

Skipper

New Member
Does this AD apply only after 400 hours of TIS? Sorry for being dense, keep reading and seems nebulous to me.
 
David

David

Active Member
jhickstx said:
Yes, I received an email from the FAA Regulatory site on 8/17/20. I was signed up to receive any ADs, SAIBs or other info for the following:

Engine|Lycoming Engines|O-360-A1P
Propeller|MT-Propeller Entwicklung GmbH|MTV-9-B
Small Airplane|Aviat Aircraft Inc|A-1C-180
--------------
https://public.govdelivery.com/accounts/USFAARGL/subscriber/new?preferences=true#tab1
Click to expand...

Thanks, I'll sign up. My A&P IA told me today the the FAA should be sending out paper notifications to all of us Husky owners. He just received his email notice yesterday.
David
 
David

David

Active Member
I just had my A&P I/A do the AD on my Husky this morning. Took about 20 minutes from start to finish, including the logbook entry. Mine is OK!
I did Service bulletin #28 years back and I am sure that took some of the strain off of the front. In Aviat's INSTRUCTIONS FOR CONTINUED AIRWORTHINESS--they state "with the aircraft in level position the stabilizers should be leveled at their rear spars by adjusting the rear struts and brace wires. The elevator hinge line should be straight and level from tip to tip" ----they go on to say "Adjust the front struts being careful not to put a twist in the stabilizers." We always use a smart level at annual to insure this is true for my Husky. I think any twist, aggravated by the prop wash would put additional strain on the front and rear stabilizer tubes. It is interesting how the front tube is attached to the frame by only two bushing and two bolts. It is not welded to the frame. Not sure why they did it that way.
David
 
Snowbirdxx

Snowbirdxx

Well-Known Member
A few comments to this issue and AD.

Most of the Husky are well maintained and in a superb condition. I have never seen such a plane having this problem. Gliding clubs use the Husky for towing and nothing else. On the gliders they do an immense amount of polishing but the Husky get totally neglected.

No diheadral

As far as the SB and rigging instructions go, absolutely no diheadral in the tailfeathers. Regardless of how smart the levelas are you will be using, there is no flat surface on the tail. . Bring the vertical fin rear post into a vertical position. Measure wingtip clearance as backup data.
Then put a L shaped aluminum ruler or wood as long as the wingspan of the horizontal stab on both of then, then measure level. Keep in mind that not all the leading edges of the elevators are straight , but we need to live with that, After adjusting , jack the tail up, put the elevaturs into neutral by squeezing a piece of cardboard between the stab and the counterbalance. Then from a distance use a ruler, hold it horizontal as a reference and visually check the tailfeathers. A human eye sometimes sees more than digital electronic devices.


The forward horizontal stab tube is bolted to the airframe. That was done during initial flight-testing to adjust the angle of incidence. Then that design was kept for easier maintenance.
A-1 and A1As have a different angle of incident then B and C models. On the A the bushings welded to the Tubes are a bit longer.

If play starts to build up in the forward tubes, its time to react. Not by tightening the bolts, but by inserting some Delrin bushings.
 
jimhusky

jimhusky

Active Member
David said:
I just had my A&P I/A do the AD on my Husky this morning. Took about 20 minutes from start to finish, including the logbook entry. Mine is OK!
I did Service bulletin #28 years back and I am sure that took some of the strain off of the front. In Aviat's INSTRUCTIONS FOR CONTINUED AIRWORTHINESS--they state "with the aircraft in level position the stabilizers should be leveled at their rear spars by adjusting the rear struts and brace wires. The elevator hinge line should be straight and level from tip to tip" ----they go on to say "Adjust the front struts being careful not to put a twist in the stabilizers." We always use a smart level at annual to insure this is true for my Husky. I think any twist, aggravated by the prop wash would put additional strain on the front and rear stabilizer tubes. It is interesting how the front tube is attached to the frame by only two bushing and two bolts. It is not welded to the frame. Not sure why they did it that way.
David
Click to expand...
Dave,
I am going to ask my A&P I/A about doing mine. If he doesn’t have time would you mind sharing the name and phone number of yours with me. If you prefer, you can send it to me at jimhusky@gmail.com.
Thank you,
Jim Jordan
 
Ak Kurt

Ak Kurt

Well-Known Member
Inspection covers are only 5-10 bucks from Aircraft Spruce, they come unpainted so you have to paint them.

Kurt
 
David

David

Active Member
After reading the new service bulletin from Aviat, and having just completed the AD; Aviat did a much better job than the FAA. The photos and instructions were crystal clear and where to look for the cracks, with the Aviat photo, was outstanding. It will make every A&Ps AD compliance inspection super easy. My hat comes off for Aviat on this one! Aviat should be able to get rid of the AD by supplying a thicker walled tube and that will eliminate the cracking around the gussets. Interesting that every one Aviat documented was a glider tug.
DAVID
 
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