Reliability Adjustment Factors for Electronic Equipment

"What if" questions are often asked regarding reliability figures of merit. The tool provides a quick "back-of-the-envelope" estimate based on conversion factors found on page 105 - 107 of the USAF Rome Laboratory Reliability Engineer's Toolkit (Ref. 1), with this correction. The underlying conversion factors were developed from MIL-HDBK-217F relationships. Enter the current reliability value and then select one or more of the conversion options (environment, temperature or part quality) by setting the "From" and "To" pull-down selections.

MIL-HDBK-217F, Notice 2, Environmental Descriptions and Assumed Default Operating Temperatures

Current reliability: MTBF (Hours): Failure rate (FPMH):

Conversion	From	To	Characteristics
Environment	Ground Benign (GB) Ground Fixed (GF) Ground Mobile (GM) Naval Sheltered (NS) Naval Unsheltered (NU) Airborne Inhabited Cargo (AIC) Airborne Inhabited Fighter (AIF) Airborne Uninhabited Cargo (AUC) Airborne Uninhabited Fighter (AUF) Airborne Rotary Wing (ARW) Space Flight (SF)	Ground Benign (GB) Ground Fixed (GF) Ground Mobile (GM) Naval Sheltered (NS) Naval Unsheltered (NU) Airborne Inhabited Cargo (AIC) Airborne Inhabited Fighter (AIF) Airborne Uninhabited Cargo (AUC) Airborne Uninhabited Fighter (AUF) Airborne Rotary Wing (ARW) Space Flight (SF)	Represents changes in vibration, shock, number of temperature cycles per year, high and low temperature extremes and humidity. Click here for more detailed descriptions.
Temperature	Internal ambient (°C) 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100	Internal ambient (°C) 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100	Represents changes to average internal operating temperatures (i.e. circuit card ambient operating temperatures).
Part Quality	Space Full Military Ruggedized Commercial	Space Full Military Ruggedized Commercial	Represents differences between component qualification and testing practices. The accuracy of this conversion estimate can also be influenced by the operational use environment (i.e. part quality can play a more significant role in harsher operating environments).

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References:

1. United States Air Force Rome Laboratory Reliability Engineer's Toolkit (1993).
2. MIL-HDBK-217F, Reliability Prediction of Electronic Equipment.
3. MIL-HDBK-217F, Notice 1, Reliability Prediction of Electronic Equipment.
4. MIL-HDBK-217F, Notice 2, Reliability Prediction of Electronic Equipment.

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