SRC Forum - Message Replies
Forum: Reliability & Maintainability Questions and Answers
Topic: Reliability & Maintainability Questions and Answers
Topic Posted by: Reliability & Maintainability Forum
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998
Posted by: LEE
Date posted: Wed Jan 16 13:53:31 US/Eastern 2002
DOES ANYBODY KNOW WHERE I CAN GET THE GPS FAILURE RATE USING FOR HELICOPTER?
Subject: GPS Reliability
Reply Posted by: B.W.Dudley
Organization: Reliablity Analysis Center
Date Posted: Mon Jan 21 15:01:25 US/Eastern 2002
After searching the web, I found a number of reliability references. Most of the data involved the operating environment of airborne commercial application. The data is as follows:
Litton -- airborne cargo 15,000 hours MTBF
Honeywell -- airborne commercial 52,000 hours MTBF
Golnas -- airborne commercial 40,000 hours MTBF
To convert to a helicopter environment, I used the translation factors from the "Reliability Engineers' Toolkit" which indicates a three to one factor. Therefore, the expected reliability should be 5,000 to 17,000 hours MTBF for the hardware.
In 1996, the National Air Traffic Service Limited, London UK, performed extensive testing of GPS units in airborne situations. Their finding indicated that the problems that one can expect are outages from many causes. most of these had no relationship to hardware reliability. The data collected for over 31,000 hours of airborne testing indicates an MTBO (mean time between outage) of 1,580 hours.