Peter Cassidy 2016

 Moisture in air  Acids in oil from combustion products

 2000 Bonanza ◦ Continental IO550 ◦ Always hangared in Nashville ◦ Flown every 2-3 weeks, 100 hrs a year ◦ Oil changed every 35 hrs, 4 months  Engine made TBO, but… ◦ Corrosion was taking a toll  Serious lifter spalling ◦ 14 years, 1610 hrs

 Susceptibility to corrosion is influenced by geographical location, season and usage.  Corrosive attack can occur in engines that are flown only occasionally regardless of geographical location.  In coastal areas and areas of high humidity, corrosive attack can occur in as little as two days.

 The best method of reducing the likelihood of corrosive attack is to fly the aircraft at least once every week for a minimum of one hour.  Of primary concern are ◦ Cylinders ◦ Piston rings ◦ Valves ◦ Valve guides ◦ Camshaft ◦ Lifters

 Temporary Storage (30-90 Days) ◦ Change Oil and fly 1 hour ◦ Spray cylinder walls with preservation oil ◦ Seal all engine openings  Indefinite Storage (Over 90 Days) ◦ Install preservation oil and fly 1 hour ◦ Spray cylinder walls with preservation oil ◦ Install dehydrator plugs ◦ Seal all engine openings

 Live in a dry climate

 Fly often  Recoats engine parts with oil  Evaporates moisture in oil  Takes about an hour  Oil needs to be 200F± for ~30 min

 Live in a dry climate  Fly often  Recoats engine parts with oil  Evaporates moisture in oil  Takes about an hour  Oil needs to be 200F± for ~30 min  Vent crankcase after shutdown

 Change oil at least every 4 months

 Use oil with corrosion inhibiting qualities ◦ Aeroshell W100 or Phillips X/C 20W-50 plus CamGuard Mike Busch EAA Webinar “All About Oil” Sept 8, 2011

 Change oil at least every 4 months  Use oil with corrosion inhibiting qualities ◦ Aeroshell W100 or Phillips X/C 20W-50 plus CamGuard Mike Busch EAA Webinar “All About Oil” Sept 8, 2011  Use engine dehydrator

 Periodically rotate the prop ◦ No longer recommended ◦ Removes oil film from cylinder walls

 Periodically rotate the prop ◦ No longer recommended ◦ Removes oil film from cylinder walls  Engine oiler ◦ Good for bearings on a cold start ◦ Does not provide splash oiling

Dew Point ºF Water Weight gr/lb

TempRHDPCorrosion Risk 140F80%132FHigh Low High Low Moderate Low Risk of corrosion is Low at 10% RH

 Tempest AA1000 ◦ $209 ◦ Feeds dry air to crankcase ◦ Single connection to engine ◦ No RH monitoring ◦ 120 VAC ◦  EICU Gen III ◦ $495 ◦ Circulates dry air crankcase and cylinders ◦ Multiple connections to engine ◦ RH monitored and maintained at 5-10% ◦ 120 VAC, built-in battery ◦

Based Minnesota, IowaBased Houston Started Using Dryer 942 hrs869 hrs 232 hrs

Hours on Engine Why did engine corrosion start at 14 yrs, 1600 hrs?

 Takes ~24 hrs to leach most of the moisture out of the engine  Desiccant needs to be recharged periodically ◦ Frequency depends on climate  Tempest will need recharging more often than EICU ◦ Check every couple of weeks  Can recharge desiccant about 20 times ◦ Bake in oven on large flat pan at 225F for 3 hrs  $15 for new desiccant pack

 When to change desiccant? ◦ Saturation varies with humidity exposure ◦ Can only be rejuvenated about 20 times ◦ EICU says 2-3 months is normal time  Check duty cycle and replace when >5% or Replace when fan runs continuous and RH above 10%

 Systems are not fail-safe ◦ When desiccant saturates humidity of circulated air increase to ambient level ◦ Can’t set and forget ◦ EICU says RH increase rate will be very slow  Checking status every few weeks will suffice

 If you don’t fly at least once a week, you’re vulnerable to engine corrosion. ◦ Signs of engine corrosion  Metal in oil filter from lifter spalling  High iron in oil analysis  Engine dehydrator reduces risk of corrosion  Eliminates need to fly plane weekly  Consistent with manufacturers recommendations  Designs have room for improvement