FAA Powerplant Written Practice Test

What precaution may be recommended for greasing a Hartzell propeller blade?

1. Using high-pressure grease only

2. Removing one of the two zero fittings

3. Applying grease to both fittings simultaneously

4. Using oil instead of grease

The correct answer is: Removing one of the two zero fittings

When greasing a Hartzell propeller blade, one recommended precaution is to remove one of the two zero fittings. This practice is important because it helps prevent over-greasing, which can lead to excessive pressure build-up within the propeller hub. By removing a fitting, it allows for adequate distribution and escape of excess grease, ensuring that the grease fills the hub evenly without creating pressure that could damage seals or cause other issues. Using high-pressure grease only is not advisable because the type of grease and its application should adhere to the manufacturer's specifications, which typically involve using specific formulary lubricants instead of emphasizing pressure. Similarly, applying grease to both fittings simultaneously could lead to the aforementioned issue of over-pressurization. Using oil instead of grease is contrary to the recommended lubrication practices for propellers, as grease is specifically designed to maintain lubrication under varying conditions and provide a protective layer against wear.