SERVICE BULLETINS

APPLICABLE TO ALL ENGINES

LEGAL NOTICE - Airworthiness - Liability - warranty


Service Bulletins contain service requirements and  instructions that are very important to flight safety and must be addressed,  complied with, or accomplished before continued flight operations. 

A “Service Bulletin“ is the equivalent of an “AD“ (Airworthiness Directive) on a Certified Aircraft. In the Experimental Regulations, no channel exists for AD’s, as such we call them Service Bulletins. These items are considered MANDATORY airworthiness items that should be fixed according to the Service Bulletin information.

A Service Letter is either a suggested change or designed as an assistant to the owner for an area where multiple difficulties arise.

ALL ENGINES

Gearboxes, Gear oil and gear oil temperatures

We do not guarantee, nor do we recommend any repairs made on the gearbox in the field, we do not sell bearings/seals - all work should be done at the Viking facility.

All 3 gear - gearboxes prior to the 48 state gearbox upgrade:

Gearbox Oil: 75W-90 or 75W-140 Mobile One Synthetic gear oil / 8 ounces. Temps could vary depending on generation of gearbox, Max temps should generally not exceed 220 F.

Viking engines should use 8 ounces of Mobile One 75W-90 or 75W-140 gear oil to ensure proper lubrication of all internal areas of the gearboxes.

All 3 gear - gearboxes with the 48 state or X gearbox upgrade:

12 ounces of gear oil should be used with the 48 state gearbox. Warning temps are at 240 F, Max Temps at 250.

Gearboxes with a sight glass measure 5 ounces to the top of the glass / visible area. You would more gear oil to meet the requirement of the gearbox generation you have. The sight glass is not a level, but is used for a visual inspection.


With 8 or 12 ounces of gear oil, oil can leak out of the gearbox vent. It is best to install a catch tank on all systems.

Be sure to monitor normal temperatures; if for any reason you see an increase in average trends, please contact Viking. Gearbox temperatures should not typically exceed 170 Fahrenheit (prior to 48 state gearbox upgrade and 240 in gearboxes with the new generation 48 state or X gearbox.

There might be instances for the temperature to be much higher; such as, climbs, lack of cooling, pusher configurations. The main point is to monitor trends, as in, the gearbox suddenly running 20 degrees hotter than in the past etc.

MANDATORY GEARBOX UPDATE

AS OF 08/04/2023

Recent improvements to the gearboxes have shown increased rigidity. The support of the internal gears has been changed from ball bearings to roller bearings which are much stronger and last longer. This change was brought into effect starting September 2022. All 2023 gearboxes are equipped with the newer and improved roller bearings. Engines with gearboxes purchased prior to September 2022 must be updated.

This update provides:

  • Increased Gear Life

  • Larger Margin of Safety

  • Provision for Increased Oil Level

  • Increased Bearing and Seal Life

  • Stronger and Longer Lasting Gearbox

This is a mandatory update for all Viking gearboxes

*All upgrades are provided at cost, plus shipping and handling.

GEARBOX VENT HOSE

Replace the gearbox vent hose with this one. It will last longer and work better with the gear oil fumes.

Amazon.com: EVIL ENERGY 3/16 Fuel Hose Line Push Lock SAE 30R7 NBR 10FT 300PSI : Automotive

WE DO NOT RECOMMEND NOR USE EARTHX BATTERIES, IT WILL COMPLETELY VOID ANY AND ALL WARRANTY. HERE IS A NICE EXAMPLE OF A CUSTOMER’S BATTERIES THAT CAUSED AN OFF-FIELD LANDING.

For the Low Winged crowd

After testing several methods to improve the flow of fuel to the centrally located fuel mini header tank, one method has been found to be superior to others.

We have yet to test with a left / right / both valve.

However, right now it works down to near no unusable fuel if each tank with two tanks feeding at the same time.

The fix was to install forward facing vents on the tanks. The original vents do not provide any pressure and might even cause a suction at times.

100LL Fuel

When using 100LL fuel in your aircraft, over time there will be lead buildup on the exhaust valve stems, causing loss of compression. It is recommended to use auto fuel. With 100 LL the use of a lead scavenger is REQUIRED, TCP or Decalin. Once your engine has lost compression due to not using the required TCP or Decalin, there is no going back and engine disassembly is required to fully remove the lead. The lead problem is not unique to just Viking, other engines such as UL, Rotax, etc. have identical problems. In fact, it is not really a problem, you just use the additive.

Powered Parachutes Using One Pump and Battery

Typical engine installations recommend the use of two fuel pumps and two batteries. This is not standard application, there are certain requirements that need to take place if continued.

Upgrade the system to a dual setup

Replace the pump every 100 hours

Fuel flow test every 25 hours

Installation of fuel pre-filters

All header tanks, containing our in-tank fuel pumps are equipped with small filters built into the pumps. These are not adequate over time, and therefore external pre-filters, available from Viking, must be installed to ensure proper fuel flow is maintained. To verify proper fuel flow, disconnect the fuel hose on the engine and place it in a measuring cup. With the engine off, engage one fuel pump at a time. The flow should be approximately one ounce per second. Normally the test is done over a 15 second period so 12 - 18 ounces should be expected. This test should be completed at every yearly condition inspection.

Fuel Flow

Please be sure to check required fuel flow, especially if pre-filters are not installed as required by Viking. You should have results that equate to 2 Quarts/Minute. If you have questions on how to perform this test, please email or call us.

The procedure is :

  • Make sure fuel pumps are off.

  • With a rag over the quick disconnect or the banjo fitting, located at the end of the rubber fuel line at the high pressure pump on the engine, remove the connector/fitting from the pump.

  • Insert the end of this hose into a calibrated container and have a helper turn the fuel pump on for exactly 1 minute.

  • Results should be approximately 2 quarts.

ALL ENGINES WITH PUMPS THAT ARE MOUNTED FROM THE BOTTOM, NEED TO HAVE THIS PRE-FILTER REMOVED - NEEDS TO BE CHECKED IF FUEL SYSTEM WAS PURCHASED IN 2020 OR PRIOR

Trimming of the Exhaust

The provided exhaust pipe is usually too long, it should be trimmed so it sticks out of the cowling approximately two inches to avoid propeller pulses from damaging the pipe as well as an exhaust brace.

Prop Strike

In the instance you have a prop strike, the gearbox must come back to Viking for inspection, and the torsion damper and centering bushing must be replaced at minimum.

REMOVAL AND RE-INSTALLATION OF GEARBOX

This should only be done if consulted with Viking. A new centering bushing is 100% required when re-installing.

Larger Radiator/Additional Cooling - If Needed