B737 Technician reported that an EA (Engineering Authorization) does not have a sufficient fuel nozzle leak check process after fuel nozzle post-replacement work is completed. If the leak test is not performed and a potential problem goes undetected; the reporter states that it can lead to in-service engine fires.

Narrative

EA (Engineering Authorization) doesn't require sufficient fuel nozzle leak check to prevent possible in-service engine fires. Nitrogen leak check with a leak test solution is a CFM best practice" but has not been adopted by Company A in this EA; nor has Boeing included it in the remove and replace of the nozzles in their AMM (Aircraft Maintenance Manual). The nitro leak check can be found in the adjustment/test section just after fuel nozzle section. This nitrogen leak test needs to be included in the Leap 1B Fuel Nozzle post replacement work card.Proof is a recent incident. During the required "idle leak check" after full set of fuel nozzles were replaced; our technicians discovered an oil leak; but no fuel leak. After a 70% part power engine run using bag method at drain lines; a significant fuel leak developed in the hot section. Other report [from weeks ago] of hot section fires support the need to do a best practice leak check. In the interim while tooling and leak detector liquid are on order; I feel need to require EA be revised to require a high power engine run after fuel nozzles are replaced or proper nitrogen test equipment tooling and leak detector can be used.Suggested resolution - an immediate resolution. In the interim; while tooling and leak detector liquid are on delay due to availability of leak check - not owned - and tooling repairs needed; I relay this feedback from the technicians on the floor: Require EA be revised to require a high power engine run after fuel nozzles are replaced and a subsequent opening of the core cowls to inspect for fuel stains; leaks in manifold; and nozzles area."