FAQ's - Performance

I know WING-X STOL will increase the GTOW on my aircraft but what will it do to performance at these higher weights?

Your kit will increase your wing area by 12.4 square feet offering additional lifting capacity even at the higher weights in fact all flight tests and performance data was conducted at these higher weights with full forward GG loading to simulate worst case scenarios. It was found that our modification will out perform all other STOL kits at these weights.

With 3 feet more wingspan, wont I loose some airspeed?

NO, there is very little drag associated with the wing extension. The additional lift coupled with the slight center of pressure change over the wing allows the aircraft to cruise at a slightly lower angle of attack which easily compensates for any associated drag. Comparison test flights were conducted at higher and lower weights on all approved model Cessna aircraft with and without wing extensions. We discovered that for the same cruise power setting, the IAS remained the same and in some cases increased. Ex. C-185 and C-206 increased 1 to 2 mph. IAS

Will WING-X STOL shorten my take off run?

YES, takeoff runs vary according to aircraft model and configuration, however you can expect to see a noticeable improvement in your aircraft's performance, especially in takeoff distance and climb rate. At the newly approved GTOW the C-180 and 182 takeoff run time will be reduced by approx. 25% on wheels, the Cessna 185 by 35% and the Cessna 206 by 30-35%.

I fly only on floats how much will WING-X STOL shorten my take off run?

The higher lift afforded by the additional wing allows the aircraft to get onto the step much quicker, then acceleration over the water is increased considerably. Takeoff runs vary according to aircraft model and type of floats, but at the higher GTOW the C-180 and 182 takeoff run time will be reduced by approx. 20-25% , the Cessna 185 by 30-35% and the Cessna 206 by 30-35%.

I fly at high elevations will WING-X STOL help my climb performance?

YES. The additional 3 feet wingspan increases the aircraft climb and glide ration. With WING-X STOL your climb performance will increase by 12-15% and service ceiling will increase by approximately 1,000 Feet depending on aircraft model.

In winter, I store my A/C in a "T" hangar ( 38'wide). How can I fit my A/C in with your mod?

Your all metal wingExtensions are structurally installed but easily removable "just like wing tips". For ease of storage they can be removed in less than 15 minutes . However removal and installation requires a tech log entry and signature by an AME.

What is the GTOW weight limitation with WING-X STOL on floats?

The GTOW of the of WING-X STOL will increase you max approved GTOW to 2,950 Lbs. on all C-180,182's and 3,525 Lbs. on all C-185's. Float buoyancy limitations still apply.In order to determine the max allowable take off weight for specific floats , divide the float size by 0.9

Example #1
Model EDO 2960, Float size = 2,960 lbs.
Maximum take off weight = 2,960 / 0.9 = 3288,88 lbs.

Example #2
Model EDO 3440, Float size = 3,440 lbs.
Maximum take off weight = 3,440 / 0.9 = 3,822,22 lbs.

Will my early model Cessna 185 with original IO-470 engine get a gross weight increase?

NO ,The early model Cessna 185 was equipped with IO-470 engine developing 260 HP. This lower power engine combined with our Wing-X STOL modification will offer you great performance but no gross weight increase. The higher gross weight of 3525 Lbs applies ONLY to aircraft that have been modified with IO-520D engine or other engine rated at 300 HP or greater.

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FAQ's - Installation

Basic info on the SPAR reinforcement kit

The reinforcement kit is an integral part of the installation procedure of a WING-X STOL kit. This design and reinforcement is not approved to be sold separately.The WING-X STOL installation must be completed by an approved shop and preferably done by a person with sheet metal and riveting experience. The job must also be followed up with proper forms and documentation such as form (FAA #337). The complete kit takes approx. 42 Hours to install.The aluminum wing reinforcement straps are installed on the upper spar cap centered at wing station 136.00" these straps are included in each kit along with the necessary fasteners/ rivets and form part of the initial installation procedure. Installation of the aluminum reinforcement straps is mandatory on all aircraft models equipped with WING-X STOL kits except the Cessna 206.

Stainless steel reinforcement straps and fasteners are also included in every kit . This reinforcement is applied to the lower spar cap at wing station 100.00" centered where the strut connects to the wing. The inspection procedure and if required, the Stainless Steel Strap reinforcement installation listed under Service Bulletin # SB-1-96 or AD#98-16-04 is MANDATORY for all aircraft having approved GTOW greater than 3,000 Lbs. During the initial installation process, inspection of the suspect area in both wings must be completed on all Cessna185 series aircraft. Those wings that do not have the original Cessna Corp. angle stiffener incorporated at the spar splice would require MANDATORY installation of the supplied stainless steel strap reinforcement.

Is it necessary to install the Stainless Steel Straps on my Cessna 185?

All C-185's have an approved GTOW greater than 3,000, if you are installing our kit it is MANDATORY to comply with the service bulletin. Only a visual inspection can ascertain if the straps are required or not. If, after visual inspection of each wing individually, the original Cessna Corp. angle stiffener is not present, the installation of the Stainless Steel Strap is MANDATORY as per Service Bulletin # SB-1-96 and or AD#98-16-04. If the original Cessna angle stiffener is present then an entry should be made in the aircraft technical log stating that you have complied with the SB or AD and that the Stainless Steel Straps are not required in either wing.

Can I install the stainless steel strap even though the stiffener is present?

NO. If the angle stiffener is present as is the case on most C-185's built after 1973, DO NOT INSTALL the stainless steel straps because the rivets/ fasteners supplied are size and strength specific. In other words the rivets would not be long enough to make up for the additional thickness at the spar splice and you could weaken the structure by adding the strap.

Is it MANDATORY to install the Stainless Steel Straps on my Cessna 180-182?

NO. Very few C-180 and 182 aircraft would be affected by Service Bulletin # SB-1-96 or AD#98-16-04 This is because most airplanes of this series have GTOW's of 2,950 Lbs. or less. However, some late model 180,182's have GTOW's in excess of 3,000 Lbs. and these aircraft, after visual inspection, may require installation of the stainless steel straps.

Can I install the stainless steel strap on my C-180 or 182 even though I never fly over 2,950?

YES, go right ahead, it makes your wing stronger so why not! Installing the stainless steel straps only takes about 6 to 8 hours and all the parts required as well as the instructions are included in every kit. A reminder, some late model 180,182's have the original Cessna Corp. angle stiffener installed , in this case DO NOT INSTALL the stainless steel straps.

I have a Cessna 206 what reinforcement straps must be installed?

NONE... The wing assembly of the C-206 series aircraft is stronger and does not require reinforcement. Therefore the aluminum straps and the stainless straps included in every kit, are not required on the Cessna 206 series aircraft equipped with WING-X STOL.

What to do when cracks are found in the wing structure prior to installing your kit?

FIX it ! TECH NOTE: WING-X STOL makes the original Cessna wing longer and therefore increases the bending moment and stress loading. This is why we introduced a specially designed reinforcement to your existing wing spar. On occasion a few older model, hi-time, Cessna aircraft have been found to have cracks along the center rib channel in the upper spar cap area at wing station 136.00 to 172.00. This area of the wing spar assembly is always accessed during the installation procedure and any deficiencies must be repaired prior to installing your WING-X STOL kit.

Follow repair procedures set out in Section 17 of the Cessna Service Manual.

How about STC compatibility with the Cessna 206 WIPTIPS and other mods?

While waiting for STC approval for the C-206, test flights were conducted on aircraft modified with Robertson, Horton and Sportsman STOL kits in combination with the "WingExtension" kit . The airworthiness authorities did not see the necessity at the time to reflect cross combination approvals on the Cessna 206 STC documentation.

The FAA issued STC for Cessna 206 is an older document and does not elaborate on cross combination approvals. It has been our experience that no one as ever questioned the compatibility of our design change when installed in combination with other leading edge devices. Wipaire does not wish to revise their STC to reflect this issue and prefers to let the installer determine compatibility. As a matter of interest , there have been numerous combined kits for the C-206 on the market for many years and the installer should have no problem in determining safety and compatibility. In some instances, in foreign countries, the local Aviation Authority may required that a flight test be carried out before final approval.

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Technical support
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Airworthiness Directive and Information

For additional information, refer to the following links:

For the U.S. DOT Federal Aviation Administration (FAA) Airworthiness Directive (AD) No. 98-16-04 Concerning Air Research Technology Wing Extensions, go to;

For searching an Electronic Version of Transport Canada Airworthiness Directive (AD) No. CF-96-17, please go to;

The Australian CASA CIVIL AVIATION SAFETY AUTHORITY version can be downloaded as well with reference to AD/CESSNA 185/45 Wing Lower Spar Cap Angle Stiffener 12/98 or go to;

FAA approved model list Cessna 170,172,175
Service Bulletin
Service Bulletin
Service Bulletin
Instructions for Continued Airworthiness (ICA) & Maintenance Manual Supplement ( MMS )
WING-X STOL Installation Instruction Guides
Installation drawings for Cessna 180,182,185
drawing 1582   drawing sb1
Installation drawings for Cessna 170-172-175
drawing 1582   drawing sb1
Flight Operating Manual Supplements FOMS
    fom 205 210
View of the Cessna Angle Stiffener
For all other questions:
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