Service Bulletins

Description:
Bend Radius in 0.032” Thick 6061-T6 Parts: Sonex has identified that certain part numbers shipped between April 26, 2023 and April 26, 2024 produced from .032” thick 6061-T6 aluminum have been formed by a vendor with an inconsistent bend radius, sometimes significantly less than 1/16” interior radius.

Parts Affected:

• SNX-F03-08 Sonex Rear Spar Shear Angle
• SNX-F10-11 Sonex Aft Lower Cabin Clip
• SNX-F22-04 Sonex Aft Shear Web Angle
• SNX-T13-06 Sonex Rudder Angle
• SNX-W04-12 Sonex Aileron Angle
• WIX-F25-04L Left Hand Clip
• WIX-F25-04R Right Hand Clip
• WIX-F25-09L Left Hand Clip
• WIX-F25-09R Right Hand Clip

Corrective Action:
Sonex has directly contacted all customers who have received shipment of the parts listed above during the specified timeframe with instructions to conduct a mandatory inspection and report back to tech@sonexaircraft.com with their findings. Sonex will assist the affected customers in evaluating parts, will advise whether replacement is necessary, and will provide replacement parts at no-charge.

General Advisories for All Builders:
Bend Radius is an extremely important component of acceptable homebuilt aircraft workmanship. In all cases, bend radius specifications in Sonex aircraft plans are specifications for the INTERIOR bend radius of a part. The Sonex Technical Support Team has observed pictures submitted by builders, usually for unrelated questions, in which inadequate bend radius can be seen in builder-formed parts.

Grain Direction:
Sonex aircraft are designed to accommodate any grain direction in their formed parts given the proper (specified) bend radius is used. In cases where the bend line of a part can be made perpendicular to the grain direction of the aluminum material, the part is more resistant to cracking during forming and fatigue cracking over the lifetime of the aircraft if the bend radius is less-than specified. Grain direction parallel to the bend line is less tolerant to inadequate bend radius. Due to factors such as total length of a part, multiple bend line axis in single part, or material usage considerations such as nesting of parts to be cut from a full sheet of aluminum, not all parts can be made with grain orientation perpendicular to bend lines.

Description:
Sonex bed-type engine mount weldments for Rotax 912-series engines have been successfully flying in the field, however, Rotax engines typically exert large momentary vibrations during engine start and engine shut-down due to their gear reduction units. On installations with traditional Sonex cowlings, these momentary start-up/shut-down engine vibrations can cause contact to occur between prop hub extensions and the cowling, causing some erosion of the fiberglass cowl at the propeller opening.

Corrective Action:
Sonex has upgraded all new production Rotax 912-series motor mounts to include an additional 1/2” OD x .035” Wall 4130 Steel Tube between the most-lower diagonal tubes and the engine mount pin subassembly aft tube cluster on each side of the engine mount – See Image Links Below:

• 1/2 Inch Brace Tube Installed
• A-Model Installation Depictions
• B-Model Installation Depictions

Installation of this additional 1/2” brace tube is optional for customers seeking to minimize engine movement inside the cowling during start-up or shut-down of their Rotax engine.

Original Sonex/Rotax engine mount purchasers may receive an 18" length of 1/2” OD x .035” Wall 4130 Steel Tube at no-charge via the Sonex Web Store, which can be cut to-fit and welded to your motor mount after removing the engine.

The tube must be welded in place using accepted aircraft welding and repair practices.

Optionally, registered Sonex aircraft owners may Contact Sonex Aircraft Tech Support and request an RMA to return their motor mounts for modification at reduced cost. Be sure to reference SNX-SB-013 in your message to Sonex Technical Support.

Description:
During installation of ACV-P54-Kit Rotax Engine Mount Attach Kit, Sonex has observed Barry Mount center bushings bottoming-out during bolt torquing, which results in inadequate bushing stiffness & inadequate isolation of engine vibration.

Corrective Action:
New washers have been added to the ACV-P54-Kit package for installation per Revision B of the ACV-P54-Kit Installation Instructions, including ACV-P54-06 and ACV-P54-07 drilled-out AN970-6 washers.

Original Purchasers of the ACV-P54-Kit Rotax Engine Mount Attach Kit experiencing this issue may receive an SNX-SB-012 Washer Update package at no-charge via the Sonex Web Store.

Non-original owners of the ACV-P54-Kit Rotax Engine Mount Attach Kit may order these washers via the ACV-P54-Kit Service Parts category of the Sonex Web Store, or they may source/modify their own washers if desired.
- ACV-P54-06 Control Print
- ACV-P54-07 Control Print

Updated 08.29.23:
ACV-P54-06 and ACV-P54-07 Washers were erroneously specified to be made from AN970-5 washers whereas they should be made from AN970-6 (1.625" dia.) washers to provide a proper base of support for the Barry Mounts. ACV-P54-Kit Installation Instructions have been revised accordingly along with control prints for ACV-P54-06 and ACV-P54-07.

Unsafe Center-mounted Throttle Installations:
A common builder modification is to move the throttle (and mixture control) to the center of the cockpit, but leave the flap lever and brake lever on the left wall of the cockpit. This creates a dangerous need to change hands on the joystick during critical phases of flight (climb-out, maneuvering, landing, go-around). Moving ONLY the throttle (and mixture control) to the center of the cockpit is NOT a Sonex-approved control configuration.

The cockpit MUST be configured so one of the pilot’s hands can remain on the stick at all times while the other hand remains free to operate the other controls (throttle, mixture, flaps, brakes, trim).

Corrective Actions:
If a center-mounted throttle is necessary, the flap and brake handles (as well as mixture control and trim control) MUST be moved to the centerline of the aircraft. Sonex specifically designed the Sport Trainer (ST) modification to accommodate center-mounted controls.
- SNX-C08_OptionalCenterControls_A.pdf
- SNX-C09_OptionalCenterDetails_A.pdf

If a center-mounted throttle is not necessary, the throttle (as well as mixture control and trim control) MUST be moved to the left side of the cockpit, near the flap and brake handles.

Description:
Fuel tank distortion has been observed to various degrees, some severe.

Cause:
The fuel tanks expand up to 3% when exposed to hydrocarbons. That, coupled with the one-piece fuel tank strap (SNB-G01-10) potentially applying too much pressure on the tank, can cause buckling.

What was Updated on 10/02/2022?
Sonex has modified the mold for SNB-G02-01 fuel cells so that tanks no longer fit tightly to the aircraft upper longerons. This reduction in total width of the tank is designed to allow the fuel cell’s natural expansion with the introduction of fuel to occur unconstrained, thus eliminating tank wall distortion due to expansion.

• All SNB-G02-01 fuel cells shipped after 9/8/22 are made from the modified mold and are not subject to this service bulletin.
• Reduction in tank width does not measurably effect total fuel capacity.
• Updating to the new version of the SNB-G02-01 is OPTIONAL
• Per the section “Previously Fueled Tanks Which are Distorted” below, tank distortion may not necessarily be a problem depending upon the location and severity of the distortion.
• If you require a replacement fuel cell, please provide photos of your tank’s distortion and your aircraft serial number to Sonex Tech Support via the contact information below.
   

What was Updated on 11/11/2021?
Tank seasoning has been found to be unnecessary and has been eliminated.

The revised procedure, detailed on Drawing SNB/WXB/XNB-G01 Rev D has the unseasoned tank installed, but loosely supported by the SNB-G01-11 two-piece fuel tank straps until the tank has been exposed to fuel for a period greater than 4 weeks. Then the straps can be snugged, but not tightened. Slight fore and aft movement of the straps at the bottom of the tank should be possible -- the straps should not be tightened so much that they cannot move at all.

If your fuel tank has been installed and exposed to fuel, inspect the tank for deformation and provide photos and your aircraft's serial number to Sonex Aircraft Technical Support (tech@sonexaircraft.com). In all cases we have seen, distorted tanks remain temporarily airworthy as long as fuel level is maintained so the fuel level supply port is covered by fuel in all flight attitudes.

Corrective Action:

Un-Fueled Tanks, both Installed and Uninstalled
Sonex Aircraft has redesigned the fuel tank straps. Remove the one piece straps (SNB-G01-10) and install your tank using the two piece fuel tank straps, part number SNB-G01-11. The two-piece straps TOGETHER WITH adhering to the installation procedure detailed on drawing SNB/WXB/XNB-G01 Rev D is all that is necessary for any tank that has not been exposed to fuel. Download SNB-G01_D_Fuel_System_Install.pdf

Recently Seasoned Tanks
If your tank has been seasoned per the previous Service Bulletin, drain the fuel and let the tank dry. It will shrink back to its original size and can then be installed per SNB-G01, Rev D.

Recently Fueled Tanks that are Installed but Not Distorted
If you have fueled your tank and it is installed with the original 1-piece strap, but shows no signs of distortion, drain the fuel and replace the straps per SNB-G01, Rev D.

Previously Fueled Tanks Which are Distorted
In addition to new fuel tank straps, a new fuel tank will be provided as necessary. If your fuel tank has been installed and exposed to fuel, inspect the tank for deformation and provide photos and your aircraft’s serial number to Sonex Aircraft Technical Support (tech@sonexaircraft.com). In all cases we have seen, distorted tanks remain temporally airworthy as long as the fuel level is maintained so the fuel supply port is covered by fuel in all flight attitudes.

Description:
Sonex Aircraft has received reports from customers using SNB-P53-01 Rotax Mount Bars of excessive shock mount wear resulting in the mount bar contacting the shock mount bolt.

Corrective Action:
SNB-P53-01 Rotax Mount Bars have been replaced by ACV-P54-Kit Rotax Mount System. This system improves shock mount installation geometry and performance. This may also be resolved using alternative shock mounts such-as Barry 22001 mounts with the existing SNB-P53-01 mount bars, however, this solution has not been tested by Sonex Aircraft. The ACV-P54-Kit mounts have been successfully tested in the field.

Original purchasers of SNB-P53-01 Rotax Mount Bars interested in upgrading to the new AeroConversions Rotax Mount System may do so at no-charge via the Sonex Web Store

Customers are asked to return SNB-P53-01 Rotax Mount Bars and any unused ACV-P01-19 Rubber Shock Mounts to:

Sonex, LLC
Rotax Mount Bar SB
511 Aviation Road
Oshkosh, WI 54902

Description:
Sonex Aircraft has received reports of the screws that hold the steering arm to the caster failing. This can result in the loss of directional control during ground operations.

The risk of a failure increases if differential brakes are installed. The Sonex Aircraft Machined Tailwheel Assembly is not intended for use with differential brakes.

Corrective Action:
Sonex Aircraft began using NAS623-2-7 screw and MS21042-08 nuts in the assembly of all Machined Tailwheel Assemblies on 09/13/2018. These replace the fully-threaded screws previously used.

Units that have already been delivered can be refitted with the new hardware:

1. Remove the fully threaded screws that hold the steering arm to the caster body.
2. Drill through the threaded holes of the caster body with a #19 drill bit to remove the existing threads and enlarge the holes for the new screws.
3. Re-install the steering arm with two (2) NAS623-2-7 screws and two (2) MS21042-08 nuts.

The hardware can be sourced from numerous aircraft hardware supply sources or ordered through the Sonex Aircraft Webstore, at: https://www.sonexaircraft.com/eshop/cart.php?target=product&product_id=17717&category_id=397

Ongoing inspection:
If you continue to operate your aircraft with the original hardware, pre-flight inspections of the original hardware must be performed. Aircraft eqipped with differential brakes must be removed from service until a full-swivel tail wheel is installed or the differential brakes are removed.

Description:
Sonex Aircraft has received reports of the tri-gear Jabiru 3300 engine mounts breaking where the outer tube interfaces with the triangular bracket that supports the nose gear strut.Mandatory Inspection: All tri-gear Jabiru 3300 motor mounts must be checked prior to your next flight with a particular emphasis on the area where the tubes interface with the triangular nose strut gusset. This should be continuously checked at regular intervals after that, such as at oil changes, 25, 50, and 100 hour inspections and during the Condition (Annual) Inspection.

This area must also be inspected immediately if nose wheel vibration is detected, a hard landing is experienced, after rough field operation, or if the nose strut is stressed sideways from improper ground handling.

Any crack found must be repaired prior to your next flight.

Optional Corrective Action:
Sonex Aircraft has upgraded all new production Tri-Gear Jabiru 3300 motor mounts (identified on the plans, on packing lists, and by part label as part number SNX-P22-10) to include an additional tube. This tube, made of 3/4” diameter x .035” wall 4130 steel tubing can be added to all existing motor mounts.

Registered Sonex aircraft owners can Contact Sonex Aircraft Tech Support and request a free tube, part number SNX-P22-07, which can be welded to your motor mount after removing the engine.

The tube must be welded in place using accepted aircraft welding and repair practices.

Ongoing Inspection:
Modified motor mounts must be inspected at regular intervals, such as at oil changes, 25, 50, and 100 hour inspections, and during the Condition (Annual) Inspection.

See diagram with full service bulletin text in download:
SNX-SB-007-TRI-3300_Motor_Mount_Change.pdf

Jabiru 3300 Tri Gear Motor Mount Tube Installation instruction sheet:
Jab_3300_Mount_Tube_Installation.pdf

Description:
Sonex Aircraft has received 4 reports of the stainless steel bolts that secure the gear legs in standard gear motormounts breaking inside the titanium gear leg. All affected aircraft have logged more than 20 hours and/or more than 25 landings on turf runways. To date there have been no reports of bolt breakage on aircraft operated on paved runways. Three of the four reports have been on aircraft operating on rough runways.Additionally, over-tightening of the nuts may have contributed to these failures.

Mandatory Inspection:
Prior to each flight inspect all stainless steel bolts securing the gear legs in the motormount (standard gear) or gear mount brackets (tri-gear), as well as the stainless steel bolts that secure the axles to the landing gear legs. Minimum inspection requirement is to try to turn each bolt with a wrench, observing the nut for similar movement. The bolts must be replaced with “steel” AN hardware prior to flight if there is any indication of a failed bolt. If both the bolt and the nut turn together DO NOT TIGHTEN the nut. This is acceptable until the hardware can be replaced.

Mandatory Corrective Action:
As soon as possible, replace all stainless steel bolts with drilled “steel” AN bolts of equivalent size, and replace the AN365 elastic stop nuts with AN310-4 castle nuts and MS24665-208 cotter.

Main Gear Installation:
AN4C-30A Bolt is replaced by AN4-30 Bolt (drilled)
AN4C-17 Bolt is replaced by AN4-17 Bolt (drilled)
AN365-428 Nut is replaced by AN310-4 Castle Nut and MS24665-208 Cotter Pin

Tail Wheel Installation:
AN4C-12A Bolt is replaced by AN4-12 Bolt (drilled)
AN365-428 Nut is replaced by AN310-4 Castle Nut and MS24665-208 Cotter Pin

Install the castle nut by tightening it until it is snug and then loosen the castle nut 1/4 to 1/2 turn before installing the cotter pin. Do not over-tighten the castle nuts on installation.

Proper bolt sizes can be found in the “L” section of the aircraft blueprints. Example: Sonex drawing SNX-L01, Detail A, AN4C-17 bolts and AN365-428 nuts to be replaced by AN4-17 bolts, AN310-4 Castle nuts, and MS MS24665-208 cotter pin.

Ongoing Inspection:
After the hardware has been replaced with drilled “steel” AN hardware and castle nuts, the inspection shall be conducted at each Condition Inspection of the aircraft.

Download Printable PDF File:
SNX-SB-006-Gear Leg Bolts-Change.pdf

Description:
Sonex Aircraft has changed the wall thickness of the two lower support tubes on all motor mounts from 0.035” to 0.049”. The two lower support tubes run from the lower motor mount pins to the lower fuselage motor mount attachments.
WAS: 3/4" Diameter x .035 Wall 4130 Steel Tube
IS: 3/4" Diameter x .049 Wall 4130 Steel Tube

All motor mounts shipped from Sonex since June of 2005 have this heavier-wall tubing already installed on the motor mount. These are identified on packing lists and labeled with -08 part numbers.

In over 11 years of service (and currently 279 completions), Sonex Aircraft has received a total of 4 reports of motor mount support tubes breaking between the lower motor mount pin and the welded area that picks up the cross-tubes. 2 of these reports were on 3300 Jabiru Engine Std Gear Mounts and 2 of these reports were on 2200 Jabiru Engine Std Gear Mounts. In all 4 cases, these were found during inspections and were obvious with a visual inspection.

All Sonex, Waiex, and Xenos Aircraft that do not have -08 motor mounts installed shall visually inspect the area of the motor mount pins for cracks prior to next flight and at regular intervals not to exceed 25 hours of flight time. If area shows signs of cracks the aircraft shall be taken out of service until suitable repairs have been made.

(update 12.04.09) Alternatively, customers may purchase and install a new -08 motor mount, or make the following upgrade/repair to their existing mount: SNX-Mount-Repair.pdf

SNX-C02-10 NOSEWHEEL PUSH ROD SPRING CHECK:
Sonex Aircraft has discovered that some Sonex and Waiex Kits Shipped before May 1st, 2007 may have included the incorrect Nosewheel Push Rod Springs. All Sonex and Waiex Tri-Gear Aircraft Owners should inspect their Sonex-supplied SNX-C02-10 Springs to ensure they are correct.

A correct Nosewheel Push Rod Spring Installation looks like this:
SNXC0210_Correct.jpg

An incorrect Nosewheel Push Rod Spring Installation looks like this:
SNXC0210_InCorrect.jpg

If your Sonex Supplied SNX-C02-10 Springs are not installed yet, you may measure the inside diameter to determine if they are correct or not. The correct springs measure over 0.60" on the inside diameter:
SNXC0210_Correct_Measure.jpg

The incorrect springs measure under 0.60" on the inside diameter:
SNXC0210_InCorrect_Measure.jpg

If you determine that you do not have the correct SNX-C02-10, please Contact Sonex Aircraft Technical Support. An RMA Number will then be issued for the return and inspection of the incorrect parts. If found to be the incorrect parts, replacements will be sent to you at no charge.

CHECK ALL WELDED COMPONENTS FOR CRACKS IMMEDIATELY:
All Welded Components should be checked prior to your next flight with a particular emphasis on the motor mounts in the area of the lower mount pin attach points. These should be continuously checked at regular intervals after that, such as at Oil Changes, 25, 50, 100, 500 hour inspections and at Annual Inspection.

Note: A crack in your black powder-coated welded component will show as a bright white/gray line and any separation of the structure will be visible to the naked eye. A flashlight and magnifying glass should be used to assist in the inspection.

Any crack found must be repaired prior to your next flight.

UPGRADE OF SNX-F10-03 ANGLE:
The upper portion of the Seat Belt Cross-Tie Assembly (SNX-F10-03) is made from SNX-Z02-03 Channel Stock. Sonex,ltd suggests that SNX-F10-03 be replaced in all Sonex aircraft with a piece fabricated from 1"x1"x1/8" thick 6061-T6 Angle. This replacement part is installed in the same location and has the same fit and function as the original SNX-F10-03. It strengthens the lower seat attach area especially for those choosing to install the Lowered Seat Modification. The new part number for this piece is SNX-F10-26.

Note: This service bulletin does not apply to the Waiex or Xenos.

CHECK ALL WELDED COMPONENTS FOR CRACKS IMMEDIATELY:
All Welded Components should be checked prior to your next flight with a particular emphasis on the motor mounts in the area of the lower mount pin attach points. These should be continuously checked at regular intervals after that, such as at Oil Changes, 25, 50, 100, 500 hour inspections and at Annual Inspection.

Note: A crack in your black powder-coated welded component will show as a bright white/gray line and any separation of the structure will be visible to the naked eye. A flashlight and magnifying glass should be used to assist in the inspection.

Any crack found must be repaired prior to your next flight.

Sonex Rudder Pedal Service Check and Upgrade or Replacment:
Download all 3 pages of SNX-SB-001 in Adobe .pdf Format Below:
SNX-SB-001p1.pdf (Page 1)
SNX-SB-001p2.pdf (Page 2)
SNX-SB-001p3.pdf (Page 3)

Description:
A Xenos airframe with 624 hours developed a crack in the tail post channel. The crack was found when the top of the rudder was found to move back and forth. The part in question is:

• Xenos and Xenos-B airframes: XNS-F23-06, Tail Post Channel
• Waiex and Waiex-B: WIX-F23-06, Tail Post Channel

Inspection:
Inspect the bend in the tail post channel for evidence of cracking. An extreme example is shown here: Download: Tail_Post_Channel_WIX-XNS-SB-003.jpg

Corrective Action:

1. Replace compromised parts.
2. Assure Tail Post Channel is properly deburred.
3. Assure correct extruded hinge (MS20001P3) is installed.
4. Assure hinge is installed with no binding of the rudder.

Ongoing Inspection:
This part is readily accessible and can be inspected as part of each pre-flight inspection.

Description:
Sonex Aircraft has received reports of the supplied swaged cables for P/N's WIX-C04-01 and WIX-C04-03 are not 1/16" proud of the Nicopress Sleeve. See Assembly Instruction #10 on the attached cable control prints:

Download: WIX-C04-01-FwdRudderCable.pdf

Download: WIX-C04-03-AftRudderCable.pdf

Image of correct Nicopress Sleeve and Thimble Installation - Download: WIX-SB-002-Cable_Swage_Inspection.pdf

Note that a cable installed flush with the end of the Nicopress Sleeve is serviceable and does not present a safety hazard.

Mandatory Inspection:
All P/N’s WIX-C04-01 and WIX-C04-03 must be checked prior to your next flight for compliance with the Sonex Assembly Instructions.

Required Corrective Action:
The Registered Waiex Owner must do four things to qualify for warranty replacement:

Note: Flying aircraft will be given shipping priority.

This Mandatory Service Notice details the addition of 3 aluminum structural components to the Waiex Tail/Fuselage attachment.
Download: WIX-SB-001_drawing.pdf

History:
Sonex, LLC conducted a design review applying a different design load criteria than was originally defined and complied with in FAR part 23. As a result of this review the design team determined this Service Notice of Modification was necessary to enhance and ensure the continued safety of the Waiex fleet.

Warning:
All Waiex Aircraft flights done without complying with this Service Notice are AT YOUR OWN RISK!

Service Parts:
Sonex has sent all Waiex Kit Customers the parts necessary to install this structural upgrade at no cost.

Description:
Waiex-B and Sonex-B aircraft utilize Electric Linear Flap Actuators. Waiex-B Kits shipped with SNB-C05-10 Feedback Linear Actuators with a retracted length of 10 13/16" hole-to-hole experience an interference of the RH Waiex rudder cable with the flap actuator when installed with SNB-F18-03L&R Flap Actuator Mounts.

Disposition:

• Sonex-B Owners: No Action Required. Reference drawings SNB-F18 Rev E, SNB-C05 Rev B and SNB-C01 Rev D if actuator upgrade is desired.
• Waiex-B Owners with SNB-C05-10 Non-Feedback Linear Actuators (9 25/64" retracted length, hole-to-hole): No Action Required. Reference drawings WXB-F18 Rev E, WXB-C05 Rev B and WXB-C01 Rev D if actuator upgrade is desired.
• Waiex-B Owners with SNB-C05-10 Feedback Linear Actuators (10 13/16" retracted length, hole-to-hole) installed with SNB-F18-02L&R Flap Actuator Mounts: Corrective Action Required – Full Flap Travel is Restricted by Fuselage Floor.
• Waiex-B Owners with SNB-C05-10 Feedback Linear Actuators (10 13/16" retracted length, hole-to-hole) installed with SNB-F18-03L&R Flap Actuator Mounts: Corrective Action Required – RH Rudder Cable Will Contact Flap Actuator.

Corrective Action:

1. Upgrade to SNB-C05-11 Electric Flap Actuator and SNB-F18-04L&R Flap Actuator Mounts:
   • Original Waiex-B owners may receive parts at no-charge via the Sonex Web Store by ordering WXB-SB-001.
   • Non-original owners may order WXB-SB-001-Used via the Sonex Web Store at reduced cost.
2. Remove and modify the SNB-C04-09 Flap Drive Tube to SNB-C04-11 Flap Drive Tube configuration using the following drawing and re-install the flap drive tube.
   • Download: SNB-C04-11_CONVERT.pdf
   • Download: WXB-C05_B_Flap_System_Details.pdf
3. Remove existing Flap Actuator Mounts and Install new SNB-F18-04L&R Flap Actuator Mounts:
   • Download: WXB-F18_E_Tail_Cone_Assembly.pdf
4. Install SNB-C05-11 Electric Flap Actuator.
   • Download: WXB-C01_D_Controls_Instl.pdf

Description:
A Xenos airframe with 624 hours developed a crack in the tail post channel. The crack was found when the top of the rudder was found to move back and forth. The part in question is:

• Xenos and Xenos-B airframes: XNS-F23-06, Tail Post Channel
• Waiex and Waiex-B: WIX-F23-06, Tail Post Channel

Inspection:
Inspect the bend in the tail post channel for evidence of cracking. An extreme example is shown here: Download: Tail_Post_Channel_WIX-XNS-SB-003.jpg

Corrective Action:

1. Replace compromised parts.
2. Assure Tail Post Channel is properly deburred.
3. Assure correct extruded hinge (MS20001P3) is installed.
4. Assure hinge is installed with no binding of the rudder.

Ongoing Inspection:
This part is readily accessible and can be inspected as part of each pre-flight inspection.

Description:
Sonex Aircraft has received reports of the supplied swaged cables for P/N's XNS-C04-02 and XNS-C04-07 may not be 1/16" proud of the Nicopress Sleeve. See Assembly Instruction #10 on the attached cable control prints:

Download: XNS-C04-02-FwdRudderCable.pdf

Download: XNS-C04-07-AftRudderCable.pdf

Image of correct Nicopress Sleeve and Thimble Installation - Download: XNS-SB-002-Cable_Swage_Inspection.pdf

Note that a cable installed flush with the end of the Nicopress Sleeve is serviceable and does not present a safety hazard.

Mandatory Inspection:
All P/N’s XNS-C04-02 and XNS-C04-07 must be checked prior to your next flight for compliance with the Sonex Assembly Instructions.

Required Corrective Action:
The Registered Xenos Owner must do four things to qualify for warranty replacement:

Note: Flying aircraft will be given shipping priority.

This Mandatory Service Notice details the addition of 1 aluminum structural component to the Xenos Tail/Fuselage attachment.
Download: XNS-SB-001_drawing.pdf

History:
Sonex, LLC conducted a design review applying a different design load criteria than was originally defined and complied with in FAR part 23. As a result of this review the design team determined this Service Notice of Modification was necessary to enhance and ensure the continued safety of the Xenos fleet.

Warning:
All Xenos Aircraft flights done without complying with this Service Notice are AT YOUR OWN RISK!

Service Parts:
Sonex has sent all Xenos Kit Customers the parts necessary to install this structural upgrade at no cost.

PBS TJ100 Idle Speed Change and Turbine Wheel & Nozzle Wheel Inspection - Mandatory Service Bulletin (Supersedes 12/19/2019 Service Bulletin)

PBS has issued the following MANDATORY SERVICE BULLETIN requiring more frequent inspection of turbine blades via endoscope, and changing the minimum idle speed of the engine from 34,000 RPM to 37,000 RPM. Borescope inspections can be conducted by the aircraft owner and should be conducted every 25 operating hours or every 30 starts. Pilots are instructed to not use minimal engine speed on the ground. Engines must be run at a minimum of 64 percent RPM. Engine serial numbers affected are listed in the service bulletin. Download: PBS_TJ100E3S_Service_Bulletin_B19311066_rev_1.pdf

Inspection Procedure

Inspection Procedure is detailed in the PBS TJ100 engine manual (section 6.8 for TJ100E3S). Manual excerpt detailing procedure available here: Download: TJ100E3S_PP-22E3S_borescope_inspection_excerpt.pdf

This inspection must be documented in your engine’s logbook at each inspection.

Sonex has updated the SubSonex Inspection Program fillable PDF in-accordance with this revised PBS service bulletin. Download: Inspection_Program_Template-Fillable_SubSonex_JSX-2_RevB_101024.pdf

Elevator Travel Limited by Elevator Stop Bracket

Description:
Reports indicate some SubSonex airframes have been unable to achieve proper up elevator travel. While incorrect angle measuring and other builder errors have caused some restrictions, Sonex Aircraft has identified that the notch in the Elevator Stop Bracket may be too small on some aircraft to permit full motion of the JSX-C02-02 Elevator Pivot Frame.

Corrective Action:

1. Remove 1/16” of material from the bottom and forward edge of the notch in the Elevator Stop Bracket located on the left side of the fuselage tail cone. Download: JSX2_Elevator_Stop_Bracket_Clearancing-scaled.jpg
2. Confirm minimum 20 degrees up elevator (from neutral) and minimum 9 degrees down elevator (from neutral). (Neutral elevator is achieved when the elevator counterweight is aligned with the leading edge of the stabilizer.)

SubSonex Fuel Filter Cleaning – Mandatory Service Bulletin

Description:
Due to the installation of JSX-G02-17 Explosion Suppressant Foam (ESF) cubes for the purposes of baffling in the SubSonex fuel tank, the primary fuel filter (drawing JSX-G03, Detail C) must be inspected and cleaned in the first hours of operation to remove loose ESF particles and other fuel cell contaminates such as XLPE fuel cell turnings/shavings (from drilling fuel fitting holes) that may not have been adequately cleaned out of the system during installation.

Corrective Action
The primary fuel filter, part number SUM-230100 or equivalent (Drawing JSX-G03, Detail C) must be inspected and cleaned at the following intervals after either initial construction of the aircraft, or after any maintenance/repair/replacement of the fuel cell or JSX-G02-17 ESF foam cubes:

• After Initial Engine Runs, Prior to Aircraft First Flight
• 10 Hours of Engine Operation After First Flight
• 100 Hours or Annually (per the existing SubSonex Inspection Program document published 11/19/2014)

If any debris is found in the primary fuel filter per the above inspections, the fuel pump filters (Drawing JSX-G03, Detail D) and PBS Supplied engine fuel filter, part number 170190.05 or equivalent (Drawing JSX-G03, Detail E) must be inspected and cleaned.

Loss of Fuel Pressure:
Additionally, the primary fuel filter (and subsequent filters as necessary) must be inspected and cleaned following any loss in fuel pressure.

Download:

• Image 1 (JSX-SB-007_Image-1_4560.jpg): clogged primary fuel filter screen
• Image 2 (JSX-SB-007_Image-2_4562.jpg): contaminates removed from primary fuel filter screen
• Image 3 (JSX-SB-007_Image-3_4567.jpg): residue contaminates in PBS Supplied fuel filter

Updated SubSonex Inspection Program:
These updated maintenance intervals are included in the latest SubSonex Inspection Program document, Revision A dated 01.19.21: Download (Fillable PDF)

If not already conducted during the most-recent applicable benchmark listed above, this inspection/service must be completed before your next flight and documented in your aircraft’s logbook.

Rudder Cable Bushings – Mandatory Service Bulletin

It has come to the attention of Sonex Aircraft that some SubSonex builders have not installed bushings in locations where rudder cables pass-through the airframe structure. While not specifically called-out in SubSonex plans, protection of control cables passing-through metal aircraft structure is standard building practice.

Corrective Action

All SubSonex airframes must be checked to ensure that bushings are installed at all control cable pass-through locations in the airframe. Bushings must be installed if they are not present. The following drawing identifies bushing locations. Download: JSX-SB-006.pdf

This inspection/service must be completed before your next flight and documented in your airframe’s logbook.

JSX-C02-10 Forward Rudder Cable Assembly – Mandatory Service Bulletin

Sonex has identified a problem with the swaging of the cylindrical terminal end of the JSX-C02-10 Forward Rudder Cable Assembly in some kits. The rudder cable may pull-out of the cylindrical terminal, causing loss of nosewheel steering. Revision A: Many kits have correct swaging. See updated Corrective Action below.

Corrective Action (Updated)

Send a picture of JSX-C02-10 stainless steel stop sleeve to Sonex Aircraft Product Support via the Sonex Contact Form for verification of correct swaging technique. Access through the nose gear door, reference plans page JSX-L02, Detail B to visually identify. Swaged end stop should be smooth and approximately 3/8" in length per the following image. Download: JSX-SB-005A.jpg

If the end stop is 5/16" in length, has any visible grooves, or beveled ends, it must be removed from your aircraft and sent back to Sonex Aircraft for repair.

This inspection/service must be completed before your next flight and documented in your airframe’s logbook.

Aileron Counter Balance Rear Spar Cut-out Position

Some outboard wing panels were delivered with an incorrectly positioned cut-out for the aileron counterbalance assembly. The presence of the error will be obvious to anyone fitting their ailerons. The attached drawing shows the proper cut-out for any impacted airframes.

Download: JSX-W11-08R-08L_Counterbalance_Cut-out.pdf

Nose Wheel Retaining Hardware Change

Drawing JSX-L02 (Rev G and above) implements changes to the hardware that retains the nose wheel. Although no problems have occurred to-date, these changes improve the retention of the nose wheel assembly.

It is recommended all owners implement these changes. Download: JSX-L02_RevG_Mark-up.jpg

Nose Wheel Fork Set Screw Installation – Mandatory Inspection

Drawing JSX-L02 (Rev D and prior) depicts a set screw (callout number 5, part number JSX-L02-42) that MUST engage the hole in the Clevis Pin (callout 42, part number AN394-53). Further, the set screw must be Locktited in place.

Failure of the set screw to engage the clevis pin can result in separation of the nose fork assembly. Drawing JSX-L02 has been revised (Rev E and above) to more clearly illustrate the installation of the set screw. A JPEG of the revision can be viewed here:
Download: JSX-L02_Rev_E_Detail.jpg

If your SubSonex is licensed, this modification must be completed before your next flight and documented in your airframe’s logbook.

Control System Collar Roll Pin Installation – Mandatory Service Bulletin

Sonex Aircraft have identified the need to pin the control pushrod collars to the pushrod (JSX-C03-02). Failure to do so can result in the collars moving on the pushrod if the bolts come loose, resulting in loss of positive control of the control surfaces. The linked drawing shows the modification and identifies the size of the roll pin used. A copy of this drawing and two roll pins have been mailed to each affected airframe.
This modification must be completed before your next flight and documented in your airframe’s logbook.

Download: JSX-C01-Detail_I-Rev_A.pdf