A320neo- HPV failed in OPEN position
A320FAM neo – HPV failed in OPEN position leading to BLEED FAULT
Engineering Support
Applicability:
A320FAM neo
References:
TFU 36.11.00.115: HPV failed closed issues in A320FAM neo
Liebherr VSIL ref. LS70645-36-01
TSM references (PW engines // CFM engines)
TSM 36-11-00-810-975-A/976-A // 36-11-00-810-B09-A/B10A
“Failure of the HPV of Engine 1/2 in the Open Position”
These TSM tasks are called to troubleshoot“HP BLEED-V (4000HA1(2))/SENSE LINE”and have been updated in Airnav Aug 2021
AMM references (PW engines // CFM engines):
36-11-51-720-804 // 36-11-51-720-805 “Functional test of the HPV”
36-11-51-000/400-802 // 36-11-51-000/400-803 “Removal / Installation of the HPV”, update planned for Airnav Aug 2022
36-11-51-000/400-806 // 36-11-51-000/400-805 “Removal / Installation of the HPV clip”, expected for Airnav Aug 2022
36-11-00-210-808-A // 36-11-00-210-807-A “Visual Inspection of the EBAS after the Failure of the HPV”,created in Airnav Feb 2021
80-11-00-210-803-A (PW) “FOD Inspection of the Engine Starting System After ECS Event”.
80-11-05-210-802-A (CFM) “Visual Inspection of the Pneumatic Air Starter”
80-11-03-000-801-A (PW) “Removal of the Starter Air Control Valve”
Description:
Some cases ofE/W “AIR ENG x BLEED FAULT” associated to maintenance message “HP BLEED-V (4000HAx)/SENSE LINE” have been reported by A320 FAM neo operators.
HPV PN is 70645A020001replacement solve the issue.
In some cases analysed, the bleed system experienced anHPV failed opencondition leading toisolationof the associated bleed system as per design.
Root Cause / Investigation: The root cause analysis is in progress.
At this stage, 3 main contributors are identified:
1.Graphite parts exudation(similar to TFU 36.11.00.115):HPV Internal contamination due to the use of JP1932 graphite material on both actuator seals and the pressure reducer clapper guide. Such material has been identified to release aluminium phosphate which acts as a strong adhesive on both piston seal ring and the regulation clapper. Release of aluminium phosphate has been confirmed to occur when JP1932 is subjected to high humidity and temperature environments.
2.Pistons rotationleading to alignment of the piston’s slots. This leads to an increase of closing chamber leakage. This is considered has marginal impact.
3.Butterfly seals clip failurewithpotential seal missing.Clip rupture after progressive wear at the contact to seal. Lead to loose seals(partially or fully) which are going out of HPV butterfly and migrate in EBAS (PRV, precooler inlet) and in engine part (starter valve)=>
risk of Foreign Object Debris (FOD)
Operator reported this failure mode mostly on AC fittedwith PW engines.
Today, the 3rdcontributor (Butterfly seals clip failure) is still under investigation but issue was not reproduced in shop after several tests in cycles and temperature performed by LTS.
In order to support the investigation, operators are requiredto provide the following information included:
– ECAM warnings & fault code triggered
– PN/SN of HPV
– FH/FC of HPV- Reason for removal
– HPV SFR to be provided
– HPV seal/clip condition after visual check
– Any specificities in operation of this aircraft (low cruise, short/long flights,…)
In case of clip failure and/or seal missing, additional information may be useful:
– Part missing on HPV (clip and/or % of seal)
– HPV pictures with clip defect
– FH and FC accumulated by the clips if replaced since HPV manufactured
– PFR history of ATA36 fault in previous flights (6 months) & associated maintenance actions
– HPV history on the AC position
– Engine maintenance history on the AC position
– Last flight DFDR data
Mitigation / Interim Action for clip failure (3):
1/ Dispatch in case of failure
See F/OPS part
2/ Maintenance recommendation:
In frame of troubleshooting, in order to mitigate clip failure, below actions should be performed when operator experienced “HP BLEED-V (4000HAx)/SENSE LINE” as per applicable TSMupdated from Airnav Aug 2021:
– RemoveimmediatelyHPV (with no functional test*)
– CheckHPV condition & integrityfor any sign of damage or deterioration at Clip or Butterfly Sealing Rings level (refer to pictures of typical damages in “Additional notes” part)
-If any HPV missing/damaged parts on the butterfly,inspect EBAS and ENGINE partsas detailed in TSM
These steps are important to ensure no FOD remains on AC.
*After investigation, Airbus has identified that the AMM Ref. 36-11-51-720-804/805 (functional test of the HPV) may pass successfully even in case of HPV with too high leakage. In addition, to ensure HPV clip defect is identified as soon as possible, AMM 80-11-03-000-801-A – Removal of theStarter Air Control Valve applicable to PW is under revision to add HPV removal and check for condition if any starter valve damages are identified.
3/ PREVENTIVE clip replacement:
Tools/Consumables:
PN M65725469-45 LOCKING TOOL to lock the HPV valve in open position and secure the butterfly seal in rotation
PN M65727534-10 BENDING TOOL to bend the seal clip at correct angle during installation
PN 6753-139: new clip
LOCTITE SF 7063: cleaning material
Today the tools & clip parts should be ordered at Liebherr. Preferred conditions apply for Airlines.
3.1/ In shop
LiebherrVSIL ref. LS70645-36-01released in October 2020 to all repair shops to recommend preventive replacement of the clip when HPV coming back to shop.
Clip replacement can be done as per CMM 36-12-48rev 06 released on 23 Feb 2022
3.2/ In line maintenance
The objective is to replace the clip before rupture in order toreduce the severity of the issue on airlines operation.
As most of the cases (mostly for PW) have brokenafter 2000FH from last clip replacement, A/L can use this threshold to define their interval and adapt to their operation and failure experience.
IMPORTANT NOTE: Preventive clip replacement possible as per AMM only if clip is in place AND not broken.
If clip is broken, a brand new one HPV should be installed on aircraft and EBAS/ENGINE inspection should be performed AMM 36-11-51-000/400-806 (PW) // -805 (CFM)will be published in Airnav Aug 2022 (including associated IPC) toprovide instruction to cover below steps:
Remove HPV as per AMM 36-11-51-000-802 (PW) // -803 (CFM) and place it on clean table
Replace the clip
Clean the area and ensure tools are removedInstall HPV back on aircraft as per AMM 36-11-51-400-802 (PW) // -803 (CFM)
Perform applicable operational tests
Advance copies is attached to this TFU since 29 April 2022 and can also be required to DOCUMENTATION DEPARTMENT via TECH REQUEST.
Operator feedback: for Airbus/Liebherr records, should operator perform preventive clip replacement, we would be interested that operator provides the following information:
– Interval of replacement used
– MSN and AC fault history if any
– HPV PN/SN, TSN/CSN and history
– Pictures of the clip at time of removal
Terminating Action:
1. For graphite parts exudation, a modifiedHPV PN 70645A020001 AMDT A(from SN 70645-04740) isavailableand delivered to FAL from Summer 2021.This will prevent the HPV internal pollution by replacing JP1932 material by purified graphite andcover the majority of the failure.
For in-service AC, this modification is documented through a recommendedVSB 70645-36-01 dispatched on 22 July 2021.
Ensure to put the reason for removal with PFR copy when HPV are sent to Liebherr.
2. & 3. For pistons rotation and butterfly seal clip failure, the final solution is under definition with specific tests on-going to get the most promising design.
To confirm this design, full endurance test on regulator (for piston modification) and then on complete valve (for butterfly seal modification) are planned to be performed along 2022.
New design HPV PN 70645A030001 including the modification is planned forQ1 2023.
Additional Note:
OPERATIONAL INFORMATION
In the case of “AIR ENG 1(2) BLEED FAULT” ECAM alert, apply the Engine Bleed reset procedure available in FCOM/QRH PRO
ABN-[RESET] System Reset.
EFFECT ON THE AIRCRAFT DISPATCH
In the case the “AIR ENG 1(2) BLEED FAULT” ECAM alert is linked to HP BLEED-V (4000HAX)/SENSE LINE, and the troubleshooting performed by the maintenance confirms that this alert is due to a faulty HP Valve, the aircraft can be dispatched under MMEL item 36-11-07B “Engine Bleed HP Valve (HP valve secured in the closed position)”.
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