Description

Dynon Avionics has received reports from pilots who have experienced degraded airspeed indications while their Dynon Heated AOA/Pitot Probe is in operation. Dynon Avionics has identified an issue where the pitot probe is unable to adequately separate and drain water that is encountered in some flight conditions. As a result, it is possible for water to enter the pitot system and subsequently freeze in unheated areas. This can cause inaccurate, fluctuating, or zero airspeed indications.

Dynon Avionics has redesigned its heated AOA/pitot probe and is offering a replacement for all customers who have the affected equipment.

Other Considerations

Dynon Avionics EFIS products use airspeed as part of the attitude calculation. While Dynon EFIS products have the ability to use GPS as a backup to airspeed, this mode is only active when the airspeed indication is zero. During inaccurate or fluctuating airspeed indications, Dynon EFIS systems (both SkyView and D10/D100 series) may not provide a reliable attitude indication.

Applicability and Affected Equipment

This bulletin affects the Dynon Avionics Heated AOA/Pitot Probe (p/n 100667-000). The Dynon Avionics Heated AOA/Pitot system is comprised of the physical AOA/pitot probe and a separate electronic controller box. This service bulletin only affects the heated AOA/pitot probe itself. THE CONTROLLER IS UNAFFECTED.

Affected Equipment

There are two ways to determine whether a Dynon Heated/AOA Pitot Probe is affected by this bulletin. If either of the following criteria is met, your Heated AOA/Pitot Probe is affected by this service bulletin and should be returned to Dynon Avionics to exchange it for the redesigned part:

1. Any Heated AOA/Pitot Probe sold before October 2014 is affected by this service bulletin.
2. Any Heated AOA/Pitot Probe with a serial number lower than 6000 is affected by this service bulletin. On affected Heated AOA/Pitots, the serial number is etched on the mounting flange that is normally recessed into a mounting bracket. The Heated AOA/Pitot Probe’s controller has its own unique serial number that cannot be used to identify affected Heated AOA/Pitot Probes.

Unaffected Equipment

The following equipment is NOT affected by this service bulletin:

1. Under-wing Unheated AOA/Pitot probes are NOT affected by this service bulletin.
2. Boom mount Unheated AOA/Pitot probes are NOT affected by this service bulletin.
3. The redesigned Heated AOA/Pitot probes sold on or after October 2014 are NOT affected by this service bulletin. These have serial numbers of 6000 or greater. They can also be identified by the location of their drain holes. If your Heated/AOA Pitot has two pin-size drainage holes along the centerline, directly behind the snout, it is the latest design and is unaffected by this bulletin.

Interim Operating Recommendations

Aircraft equipped with an affected Dynon Avionics Heated AOA/Pitot probe should be operated as if the aircraft is equipped with an Unheated AOA/Pitot Probe until the Heated AOA/Pitot probe is replaced via Dynon’s Heated Pitot Exchange Program.

Solution / Method of Compliance

Dynon Avionics has updated the Heated AOA/Pitot Probe design. The new probe features a complete redesign of its water separation and draining features so that moisture is prevented from entering unheated portions of the pitot system. Dynon Avionics is making the redesigned probe available to all Heated AOA/Pitot Probe customers at no charge.

If your Heated AOA/Pitot Probe is affected by this service bulletin, please exchange it for the redesigned version by going to our Heated Pitot Replacement Form

After installation of the replacement Heated AOA/Pitot Probe, you should perform an AOA calibration on your Dynon EFIS system.

Time in Effect

This technical service bulletin is in effect indefinitely.

Costs to the Customer

Replacement Heated AOA/Pitot Probes are being provided in exchange for probes affected by this bulletin at no charge to the customer for the replacement pitot. Dynon is not responsible for costs related to the removal and installation of the pitots. The customer is only responsible for returning their existing Heated AOA/Pitot to Dynon Avionics or providing proof that the replaced pitot was destroyed. We recommend that customers not destroy their existing pitot until they have their replacement or RMA number in-hand.

Notice to Special Light Sport Aircraft (S-LSA) and Other Non-experimental Customers

You are solely responsible for ensuring that your aircraft is airworthy. In the case of S-LSA aircraft, owners may need special authorization to service the aircraft if such operations are not permitted in the maintenance manual. Please refer to your aircraft maintenance manual or contact your aircraft manufacturer concerning removing, replacing or updating your Heated AOA/Pitot Probe.

Frequently Asked Questions

Question: Now that Dynon has a solution to this issue, will I have to buy a new heated pitot?
Answer: No. Dynon is committed to supporting our customers. Dynon is exchanging affected Heated AOA/Pitot probe with the redesigned version at no charge.

Question: Do I need to send back my existing Heated/AOA Pitot?
Answer: You can either send it back to Dynon or provide proof that you have destroyed your existing pitot to avoid being charged for the replacement. Instructions for both options are included with the replacement Heated/AOA pitot. We recommend that customers not destroy their existing pitot until they have their replacement or RMA number in-hand.

Question: If I don't send back my existing Heated/AOA Pitot, how should I destroy it?
Answer: Instructions are available for download. These instructions are also included with the replacement Heated/AOA pitot. We recommend that customers not destroy their existing pitot until they have their replacement or RMA number in-hand.

Question: When do you expect to have a solution available?
Answer: The redesigned Heated AOA/Pitot Probe is now available as of October 2014. Please go to our Heated Pitot Replacement Form or contact Dynon Avionics to arrange an exchange for the new version.

Question: Can you send me a replacement Heated AOA/Pitot before I send back my existing Heated AOA/Pitot Probe.
Answer: Yes. Dynon can accommodate both normal RMAs (where you send your existing pitot to us first) or advanced replacement. In the case of advanced replacement, we obtain credit card information to secure the return or proof that you've destroyed your old pitot. We will not charge your card as long as you do one of the above within 30 days of receiving the replacement pitot. We recommend that customers not destroy their existing pitot until they have their replacement or RMA number in-hand.

Question: Does the Dynon pitot probe get hot enough?
Answer: Yes. The 120 watt heater which heats the body of the probe, including the drain holes, is sufficient to melt external ice in the conditions experienced by piston-powered Experimental and Light Sport Aircraft. Our data indicates that the root cause of this issue is inadequate water separation inside the pitot.

Question: Is there a problem with the pitot’s heat regulation?
Answer: No. The regulated heater is a safety feature which prevents the pitot from becoming dangerously hot on the ground. The regulator controls the heat output as necessary to keep the pitot probe clear of ice in sub-freezing temperatures. Though the heater system design is more than adequate to melt ice, inadequate drainage in some conditions can allow water into unheated portions of the pitot system.

Question: Since the Dynon Heated AOA/Pitot Probe system is comprised of the pitot itself and its controller module, don’t I need a replacement for both?
Answer: No. The controller module is unaffected by this service bulletin. Only the heated AOA/Pitot Probe itself is affected by this bulletin.

Question: Are the D1and D2 Pocket Panel Portable EFIS products affected?
Answer: No. As standalone backup instruments, these products use GPS ground speed as part of the attitude calculation, and are not connected to the pitot/static system.

Question: Can this issue occur if I am flying through clear air?
Answer: Yes. Pilots have reported this anomaly in clear air, but only when the outside air temperature was below freezing, and the pitot had previously encountered precipitation or otherwise ingested water (such as from washing).

Question: Does this affect the Unheated AOA/Pitot Probe?
Answer: No. The unheated Dynon AOA/Pitot (p/n 100141-000) is not designed for use in flight conditions where pitot icing is expected. Therefore, this bulletin does not apply to that product.

Question: Does this affect the unheated Boom Mount AOA/Pitot Probe?
Answer: No. The unheated Boom Mount AOA/Pitot Probe (p/n 100532-000) is not designed for use in flight conditions where pitot icing is expected. Therefore, this bulletin does not apply to that product.

Question: What are the symptoms of various pitot system failures?
Answer: There are a variety of airspeed indications that are possible with a blockage of any kind in a pitot system:

• Indicated Airspeed may go to zero. This may happen quickly or take minutes to occur.
• Indicated Airspeed may fluctuate or become erratic.
• Indicated Airspeed may become directly related to altitude. If the pitot system is completely blocked, then airspeed varies with static pressure only. In this case, as you descend, airspeed indication will decrease. If you climb, airspeed will increase. This is opposite from the normally expected reaction of airspeed which increases as a plane descends at a constant power setting.
• If you hold altitude, your airspeed indication may stay fixed without relation to the actual aircraft airspeed. This may be perceived as high or low airspeed if you have climbed or descended since the blockage occurred.
  

Additional Questions?

Contact Dynon Avionics Technical Support via phone (425-402-0433) or email support@dynonavionics.com