February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 1 Fuel and Oil Filter Delta Pressure Switch February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 2 Fuel and Oil Filter Delta Pressure Switch Background / Status Numerous QA07985 field removals MTBUR = 42,000 Hrs 36 VIN QA07995 units received @ vendor MTBUR = 54,000 Hrs Calculation uses total time accumulated by Switches introduced on production engines only Very pessimistic Using time accumulated by all switches delivered to customers MTBUR > 80,000 Hrs Reliability Increasing February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 3 Investigations Old Design : QA07985 85% removals failure modes corrected in VIN QAO7995 – SB 73-042 issued Jan 2000 – Introduced on aircraft delivered since Mar 2000 15% with no fault duplicated and assumed to be due to micro-switch erratic indications due to temperature, and vibrations New Design : QA07995 - 36 units received @ vendor 5 units (14%) found with contact resistance value out of ATP limit – Only one high enough to cause switch disagree fault 21 units (58%) tested and No Fault Found No mechanical failure identified 10 units pending testing Root Cause Suspected to Be Intermittent Indication Inherent to Micro-switch Technology Fuel and Oil Filter Delta Pressure Switch February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 4 Corrective Action • Aircraft DDG revised to allow for one (1) flight dispatch allowance prior fuel filter replacement, provided: Fault verified to be in warning system No contamination found at filter drain plug • QA07995 field implementation on-going • QA07995 failures root cause status System tests (accelerated life testing ) with harness and EEC card – Tests completed with 6 field switches but no failure duplicated • One hermetic and 3 reed switch prototypes passed engineering qualification tests Go-ahead decision when current design failure root cause will be demonstrated • Switch disagree fault logic change under evaluation Switch fault to illuminate light at the end of the flight – No change in the clogging logic If launched will be implemented in 7BO software expected by end of 2002 Fuel and Oil Filter Delta Pressure Switch February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 5 Background / Status VIN QA07656 - Same technology as the Fuel Filter DP Switch • 35 reported oil filter bypass light illumination over last 12 month 12 cases Switch fault reported, and switch replaced 13 cases NO switch fault reported, but switch replaced 8 cases NO switch fault reported, and no switch replacement reported • 34 occurred on ground / 1 in-flight and ground • 94 units received @ vendor last 24 month MTBUR = 90,000 Hrs 72 with contact resistance values above ATP limit – 34 high enough to set switch disagree fault • Additional finding Crack initiation at red wire solder joint (not separated) on 3 returned units due to heat shrinkable sleeve being too close to solder Fuel and Oil Filter Delta Pressure Switch February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 6 Corrective Action • Switch assembly procedure to be revised to move red wire heat shrinkable sleeve away from solder Reduce stress applied to the red wire • Fuel switch disagree fault logic change may be applied to the oil filter system Switch Fault to illuminate light at the end of the flight – No change in the clogging logic If launched, will be implemented in 7BO software expected by end of 2002 Fuel and Oil Filter Delta Pressure Switch February 2002 WTT face to face CFMI / Boeing Proprietary Information - Unauthorized Disclosure, Use, or Export are Prohibited 7 Summary • Fuel filter DP switch new design, and oil filter DP switch reliability increasing towards expectations • No short term solutions for remaining FFDPS, and OFDPS erratic indications/ high contact resistance Issue inherent to micro-switch technology • Hermetic and reed switch prototypes could be evaluated if current design failure root cause demonstrated • Switch disagree fault logic implementation being evaluated In 7BO software (if launched) expected by end of 2002 Fuel Filter DP Switch Reliability Increasing Oil Filter DP Switch Reliability Meeting Expectations Fuel and Oil Filter Delta Pressure Switch作者: 979199501 时间: 2011-4-16 00:00:47 标题: 回复 1# 航空 的帖子
Arm
Proposed Switch Configuration
Current Double Throw
Proposed Single Throw
Run contact eliminated
Introduction Logistics
• CFMI/Boeing/Honeywell laun作者: kinran 时间: 2011-6-4 23:18:46
