Best Practices for Aircraft Engine Preservation
Engine preservation is a critical procedure for protecting internal engine components during periods of inactivity—whether the aircraft is awaiting overhaul, in seasonal storage, or shipping to its next destination. Both Continental and Lycoming emphasize that corrosion begins rapidly when engines are not flown regularly. Preservation is essential for maintaining performance, extending TBO, and avoiding costly repairs.
MS27215-2 Dehydrator Plugs – In Stock at Air Power, Inc.
Why Engine Preservation Matters
Aircraft engines that sit idle for more than 30 days are highly susceptible to corrosion, especially in humid environments or near coastal areas. According to manufacturer guidelines:
- Corrosion can occur in as little as 48 hours
- Engines not operated to full temperature fail to boil off moisture
- Idle aircraft suffer reduced compression, early cam wear, and shortened life
Preservation helps mitigate these risks by removing moisture, sealing atmospheric openings, and protecting internal parts with corrosion inhibitors.
Short-Term Storage (30–90 Days)
- Change engine oil with preservative oil conforming to MIL-C-6529
- Ground run or fly the engine to operating temps for at least 1 hour
- Spray MIL-PRF-46002 cylinder preservative oil through top spark plug holes
- Rotate crankshaft during spraying to coat all cylinders evenly
- Install dehydrator plugs in the top spark plug holes
- Seal exhaust, intake, and breather tube with desiccant bags and tape
Long-Term or Indefinite Storage (90+ Days)
If the aircraft will not be operated for 90 days or more, perform the following additional steps:
- Repeat preservative oil application every 90 days
- Inspect MS27215-2 dehydrator plugs every 15 days
- Replace plugs if desiccant color changes from blue to pink
Always verify that the dehydrator plug is dark blue before installation.
Recommended Product: MS27215-2 Dehydrator Plug
Air Power stocks the MS27215-2 Dehydrator Plug, which meets the preservation requirements of both Continental and Lycoming engines.
- Standard 18mm thread for spark plug ports
- Filled with MIL-D-3716 desiccant
- Color changes from blue (dry) to pink (saturated)
- Reusable after heating to remove moisture
- Sold in multiples of 8 →
Apply preservation oil through spark plug ports and seal with MS27215-2 plugs.
Example Preservation Tracking Table
| Inspection Item | Status | Due Date | Completed | Technician |
|---|---|---|---|---|
| Initial Preservation | Completed | N/A | ✓ | JD |
| 15-Day Plug Check | OK | 07/10/2025 | ✓ | JD |
| 90-Day Re-Oil | Scheduled | 09/10/2025 | — | — |
| Remove from Storage | Pending | TBD | — | — |
Resources
Detailed preservation steps are outlined in:
- Continental M-0 Manual, Chapter 9: Engine Preservation & Storage
- Lycoming Service Letter L180B: Engine Preservation for Active and Stored Aircraft
You can also refer to FAA AC 20-105B and individual engine service instructions for guidance.
Need Help with Preservation Supplies?
Air Power is proud to be the world’s largest Continental Engine distributor and a top supplier of Lycoming engines and factory parts. We stock MS27215-2 plugs, Tempest preservation products, and a full line of desiccant, spark plugs, gaskets, and shipping caps.
For more information or to order your preservation supplies, contact us today or visit the product page for MS27215-2 Dehydrator Plugs.