General Aviation Aircraft Empennage Flight Loads 1999-01-1573

ACE-100 provides the accepted method for estimating the fatigue life of empennage structures. It is based on airplane normal accelerations at the center of gravity (CG Nz). While there is a strong correlation between CG Nz and wing loads, little correlation exists with empennage loads. A Cessna 172P was instrumented for this flight loads program. It was found that significant loads were induced in the horizontal and vertical tails during roll and dutch-roll maneuvers indicating that the fatigue load spectra derived using ACE-100 may significantly underestimate the fatigue cycles experienced by the empennage. In addition, a method for monitoring in-flight tail loads was developed that does not require the installation of strain gages on each airplane.