Attention all Owners

As many of you may already know, Safety Alert SA0009 was released today and it applies to all CC11 aircraft. It has been posted on the Support page of our website and a copy is being mailed to each owner today. Included with the mailing is the letter below from CEO/Founder, Jim Richmond and General Manager, Randy Lervold. The mailing also includes the instructions listed below for internet users to do backordering online and any necessary updating of owner information. As your Customer Support Manager, please feel free to contact me should you have any questions or concerns. Your continued support of CubCrafters is very much appreciated as finalization of this safety alert is underway.

Regards

Jeff Glab
Customer Support Manager



DATE: November22, 2013
TO: All CC11-100 and CC11-160 aircraft owners

At CubCrafters we take our responsibility for the operational safety of our products seriously. With this letter you will find enclosed a Safety Alert that applies to the entire CC11 airframe family (CC11-100 Sport Cub & CC11-160 Carbon Cub). Safety Alert 0009 (SA0009) relates to the tail support wires installed on these airframes. CubCrafters’ first priority is our customers’ safety, and we have chosen to exercise an abundance of caution by issuing this Safety Alert at this time.

Initial failure and background
Earlier this year a new Carbon Cub on a delivery flight from the factory to the East coast experienced a failure in one of the upper tail brace wires. The failure was in the threaded portion of the wire and was discovered after an en-route landing. As soon as Cub Crafters was notified, the customer was sent replacement parts and asked to return all four wires as soon as possible. The wires were sent to our metallurgy lab and a detailed investigation was initiated that included:

· Detailed metallurgical analyses ofthe parts
· Consultations with the suppliers ofthe raw stock and the vendor that rolled the threads
· An investigation of production procedures used to set the tension in the wires
· An examination of the assembly and inspection records of the aircraft

The metallurgical investigation showed that a crack had initiated in the threaded part of the wire. No cracks were found in the other end of the affected wire or in the other three wires. Other wires from the same batch as the affected one, plus a selection of wires removed from aircraft in service, were examined. No others showed evidence of cracking.

At the time this was the only reported incident of its kind, despite the fact that there were several aircraft with more than 1000 hours in service, and a few more nearing 2000 hours. CubCrafters therefore concluded that this was an isolated incident where the wire had been somehow mishandled in such a way that a crack had started. One possibility was that this could have occurred during ground handling when someone may have pushed on the wire, a practice that CubCrafters very strongly discourages.

Second instance
A few weeks ago there was a second incident of a tail wire failure, this time on a CubCrafters company owned Sport Cub with about 1300 hours total time. As before, the broken wire was discovered after landing, and as before the failure was in the threaded part of the wire.

The Continued Operational Safety Committee atCubCrafters was convened for an urgent meeting to review the issue and the following action plan was crafted:
1. Contact selected high-time aircraft owners to collect data on airframe flight time. Send those owners new wires, asking them to return the old ones for analyses.
2. Carry out flight tests on CC11-100 and CC11-160 aircraft to determine if there are any flight regimes where the wires could be subjected to cyclical bending loads that could start a crack and induce a fatigue failure.
3. Carry out flight tests on a CC18-180 Top Cub for comparison to the CC11 design and to establish a baseline. (The design of the attachment of the wires on the CC18 is different than the CC11 and is identical to the Piper PA-18’s. This is a tried andtrue design that has no history of problems.)

Analysis & new design
In addition to our own engineering team, we have sought assistance from well-known and experienced outside engineers (DERs) to supplement our efforts to analyze the root cause of this issue and devise alternative designs. This combined internal/external team has been working as quickly as possible.

Testing has consisted of strain gauging the flying wire system, conducting test flights through all flight regimes, and analyzing the stress data. We have now analyzed enough data collected during these tests to conclude that in certain phases of flight the wires on the CC11 aircraft experience oscillations that induce high cyclical stresses in the wires.

Two designs have been developed in parallel and are being flight tested and evaluated simultaneously. Until these tests are complete however, we will not know which design assures a confirmed and permanent solution. Once the design is confirmed and frozen we will begin manufacturing parts kits around the clock as well as finalizing detailed installation/retrofit instructions.

Fleet retrofit plan
Our estimate is that the final design will be complete and parts will be available in a matter of weeks. Permanent structural integrity and ease of installation are the paramount considerations. At the time the design is finalized SA0009 will be revised to include specifics of the retrofit program as well as installation instructions. As has been our policy we will provide both parts and labor at no charge for aircraft currently under warranty. For aircraft out of warranty a parts kit will be available at our cost, and installation labor will be the responsibility of the owner. We understand that owners of aircraft out of warranty may find this objectionable.We ask that they consider that virtually all aircraft manufacturers have to employ this same policy.

Applicability
Many aircraft in our CC11 fleet have been converted to E-LSA certification. Legally, owners of these aircraft are not bound by Safety Alerts. However, in the interest of safety, we strongly recommend that all owners install the retrofit kit. Our Carbon Cub EX kit & CC-18 Top Cub aircraft use a PA-18 style tail brace wire system that is unaffected by this Safety Alert.

Safety!
This brings us back to CubCrafters first priority: our customers’ safety. We are issuing SA0009 before a final solution is available with our owners’ safety in mind, and out of an abundance of caution. Please be assured that CubCrafters is working diligently to finish an improved tail wire design for retrofit on all CC11 aircraft as fast as possible.

Please note that the Safety Alert states that the aircraft may be flown no more than 10 hours before the modification isinstalled. This is intended to allow owners to ferry their aircraft to a facility where the work can be carried out. Again, a revision of the Alert with retrofit specifics will be issued very soon when the design has been finalized and tested.

We ask for your understanding and patience aswe complete the retrofit design and program. We regret having to issue this Safety Alert and know this temporary constraint on use will pose an inconvenience. After much deliberation however, we feel this cautious approach is warranted. Please know that finalization of this program is our team’s top priority.

Thank you for your understanding and cooperation,

Jim Richmond
CEO/Founder

Randy Lervold
General Manager



INTERNET USERS

To be placed on a backorder queue for SA0009 please follow these instructions:

1. Go to www.cubcrafters.com.
2. Click on “Pilot Shop” at the top center of the screen.
3. Click on “click here to order Safety Alert SA0009.”
4. Check the warranty box if your aircraft is within the one-year warranty period from the date SA0009 was released.
5. Enter your aircraft registration number.
6. Enter quantity.
7. Click “add to cart.”
8. Click “proceed to checkout.”

Ordering by this method will put you in the queue to have it shipped when the parts become available.

If you are no longer in possession of this aircraft, please follow these instructions for change of ownership:

1. Go to www.cubcrafters.com.
2. Click on “Support” at the top of the page.
3. Click on “Owner Support.”
4. Scroll down to “Ownership Forms.” It will be in right hand column.
5. Click on “Change of Address/Ownership Form.”
6. Fill out all required boxes.
7. Click on “Submit.”

By following these steps this form will automatically be sent to CubCrafters Customer Support to allow for update of our aircraft ownership database.

Thank you for your understanding and cooperation,

Jeff Glab
Customer Support Manager
Cub Crafters, Inc.