Selection Criteria - PSE

(1) The factors used to find the PSE's  include:

(a) Service Experience

1 Multiple sources of information were used to find the service discrepancies.

a Cessna Service Bulletins and Service Information Letters issued to repair common service discrepancies were examined.

b FAA Service Difficulty Records and Foreign certification agency Service Difficulty Records were examined.

2 Existing analyses were reviewed to identify components in areas that may have exhibited the potential for additional inspection requirements.

3 A review of test results applicable to the design was made to identify the critical areas of the PSE's.

3. Usage

A. Aircraft Usage

                      (1) Aircraft usage data for the SID program is based on the evaluation of the in-service utilization of the aircraft. This data was used to develop the representative fatigue loads spectra. Operational data for development of the Supplemental Structural Inspection Program was obtained from surveys of aircraft operators.

                     (2) Usage for spectra determination is defined in terms of a single flight representing typical average in-service utilization of the aircraft. This usage reflects the typical in-service flight variation of flight length, takeoff gross weight, payload and fuel.

                     (3) The flight is defined in detail in terms of a flight profile. The profile identifies the gross weight, payload, fuel, altitude, speed, distance etc., required to define the pertinent flight and ground parameters needed to develop the fatigue loads. The flight is then divided into operational segments, where each segment represents the average values of the parameters (speed, payload, fuel etc.) that are used to calculate the loads spectrum.

B. Stress Spectrum.

                  (1) A fatigue loads spectrum, in terms of gross area stress, was developed for each PSE to be analyzed based on the usage-flight profiles. The spectrum represents the following loading environments: flight loads (gust and maneuver), landing impact, taxi loads and ground-air-ground cycles. The resulting spectrum is a representative flight-by-flight, cycle-by-cycle loading sequence that reflects the appropriate and significant airplane response characteristics.

                (2) After reviewing the aircraft usage data and the way in which the surveyed aircraft were flown, two sets of stress spectra were developed. The first flight profile represents typical usage, while the second profile represents severe usage.