Narrative:

A gulfstream G-200 arrived with the following logbook write-up discrepancy: left engine anti-ice light EICAS message comes on with power above 95-percent and engine anti-ice is not selected. Anti-ice system checks properly on ground. In short the engine is getting [sending] bleed pressure to the [anti-ice] system; even though the switch is 'off;' which makes sense because it is a fail-safe system which fails in the 'open' position through a spring load. Since it was receiving the correct electrical signals when troubleshooting; it was determined that the valve failed 'open'. When the technicians checked the system on the ground; the troubleshooting checks found no discrepancies electrically; but they did duplicate the anti-ice 'on' at the high power run-up pad. The pressure regulating and shut-off valve (prsov) was thought to be the culprit; because of the message showing up only at high engine speeds/high pressure and was electrically operating correctly. When the left-hand engine upper and lower cowls were removed from the aircraft so they could gain access to the valve; they [cowls] were inspected visually as part of a general serviceability check. At that time a small crack was found on the left-hand upper engine cowl; this was located in the forward section of the cowl directly adjacent to the anti-ice valve. There was no discoloration on the cowl which would have pointed to a bleed leak. It was thought to be a stress crack at the time. Since no replacement cowl was available; and the aircraft was due into inspection at gulfstream's [repair station]; the most time and cost economical solution was to ferry the aircraft to the [repair station] and repair the cowl there during the inspection. Gulfstream issued a letter of 'no objection to ferry' the aircraft to the [repair station]. The crack was to be speed-taped over to provide a smooth contour. This was accomplished after the anti-ice valve was installed; operationally [checked] and leak checked. The aircraft departed on the ferry flight five days later and had a bleed air leak which damaged the eec and the engine experienced an in-flight shutdown. The aircraft returned to the local area; but landed at an adjacent airport after approximately thirty minutes of flight time.in regards to the installation of the left-hand anti-ice valve and operational/leak checks: the pressure sense line; which tee's off the lower duct; is not disturbed when changing the anti-ice valve. There is no leak check called out on either the [anti-ice] valve replacement [job] card or the functional check card. The leak check at idle speeds was complied with by the technician; but it appears at an idle setting that the engine produces such a low pressure of air that a small leak would go unnoticed. An engineering technical change request; [was submitted] to make changes to the aircraft maintenance manual (amm) and job card to reflect the requirement to perform a leak check of the [anti-ice] valve/entire system affected. This change request has already been requested through the aircraft's manufacturer. Leak checks should be at an increased power setting to ensure a leak; if present; can be identified. At idle; these leaks may not be present. Technicians should inspect an entire system/area when performing maintenance in that area to ensure its integrity. The vendor [a contract maintenance provider] in this incident has already made policy changes to that effect. The left-hand engine anti-ice pressure sense line b-nut was loose; causing hot bleed air to leak. This caused damage to the left-hand engine and an in-flight shutdown. [I am the] maintenance manager.

Related reports:

Google
 

Original NASA ASRS Text

Title: A Maintenance Manager for an Air Operator and two contracted Line Maintenance Technicians report on a Gulfstream G-200 aircraft that landed in an emergency condition after a bleed air leak had damaged the EEC causing an auto-shutdown of the left engine. Lack of a Leak Check callout on the Anti-Ice Valve Replacement Job Card and Functional Check Card were also noted.

Narrative: A Gulfstream G-200 arrived with the following logbook write-up discrepancy: Left engine anti-ice light EICAS message comes on with power above 95-percent and engine anti-ice is not selected. Anti-Ice System checks properly on ground. In short the engine is getting [sending] bleed pressure to the [Anti-Ice] System; even though the switch is 'Off;' which makes sense because it is a fail-safe system which fails in the 'Open' position through a spring load. Since it was receiving the correct electrical signals when troubleshooting; it was determined that the valve failed 'Open'. When the technicians checked the system on the ground; the troubleshooting checks found no discrepancies electrically; but they did duplicate the Anti-Ice 'On' at the high power run-up pad. The Pressure Regulating and Shut-Off Valve (PRSOV) was thought to be the culprit; because of the message showing up only at high engine speeds/high pressure and was electrically operating correctly. When the left-hand engine upper and lower cowls were removed from the aircraft so they could gain access to the valve; they [cowls] were inspected visually as part of a general Serviceability Check. At that time a small crack was found on the left-hand upper engine cowl; this was located in the forward section of the cowl directly adjacent to the anti-ice valve. There was no discoloration on the cowl which would have pointed to a bleed leak. It was thought to be a stress crack at the time. Since no replacement cowl was available; and the aircraft was due into inspection at Gulfstream's [Repair Station]; the most time and cost economical solution was to ferry the aircraft to the [Repair Station] and repair the cowl there during the inspection. Gulfstream issued a letter of 'No Objection to Ferry' the aircraft to the [Repair Station]. The crack was to be speed-taped over to provide a smooth contour. This was accomplished after the anti-ice valve was installed; operationally [checked] and leak checked. The aircraft departed on the ferry flight five days later and had a bleed air leak which damaged the EEC and the engine experienced an in-flight shutdown. The aircraft returned to the local area; but landed at an adjacent airport after approximately thirty minutes of flight time.In regards to the installation of the left-hand anti-ice valve and Operational/Leak Checks: the pressure sense line; which tee's off the lower duct; is not disturbed when changing the anti-ice valve. There is no Leak Check called out on either the [Anti-Ice] Valve Replacement [Job] Card or the Functional Check Card. The Leak Check at idle speeds was complied with by the Technician; but it appears at an idle setting that the engine produces such a low pressure of air that a small leak would go unnoticed. An Engineering Technical Change Request; [was submitted] to make changes to the Aircraft Maintenance Manual (AMM) and job card to reflect the requirement to perform a leak check of the [anti-ice] valve/entire system affected. This Change Request has already been requested through the aircraft's Manufacturer. Leak checks should be at an increased power setting to ensure a leak; if present; can be identified. At idle; these leaks may not be present. Technicians should inspect an entire system/area when performing maintenance in that area to ensure its integrity. The Vendor [a Contract Maintenance Provider] in this incident has already made policy changes to that effect. The left-hand engine anti-ice pressure sense line B-nut was loose; causing hot bleed air to leak. This caused damage to the left-hand engine and an in-flight shutdown. [I am the] Maintenance Manager.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.