Airbus Manual Wing Corrosion
SDR # 6 Flight Spoiler PCU Rod End Failure SDR submitted: During flight, a R/H spoiler panel began to float freely where maintenance discovered the #2 R/H Spoiler Actuator threaded rod end assembly had failed and separated from its adjoining PCU housing. Prior to this finding on the previous flight, a Minimum Equipment List (MEL) deferral for a #2 & #3 spoiler fault was applied and the aeroplane was dispatched. The flight spoiler PCU actuator was replaced, MEL removed and the aeroplane was made serviceable. Transport Canada Comments: The information on this finding has been forwarded to Airbus for further investigation.
Transport Canada Civil Aviation (TCCA) would like to remind all operators of the importance to ensure for correct aircraft system integrity prior to applying MEL deferrals. SDR # 3 Passenger Door Seat Retainer Corrosion SDR submitted: The aeroplane passenger door seal had a small tear in it causing a pressurization leak. Upon maintenance inspection when the door seal was removed, corrosion was noted.
A further inspection found extensive corrosion through the skin with a width of 2.5 cm (1 in) by 1.27 cm (1/2 in) on the top of the door seal retainer under the seal. A repair was carried out, the corrosion removed and the aircraft was made serviceable. Transport Canada Comments: BAE United Kingdom being the Type Certificate Holder (TCH) of this aircraft and as noted from the operator, have issued Information Letter 52-J31-J32-664-1 and revised the maintenance program to define a more specific inspection task for the passenger door. Transport Canada Civil Aviation (TCCA) would like to advise all owners and operators of this aeroplane model to be aware of this possible corrosion and BAEs corrective action to address this issue. SDR # 2 Elevator Auto Pilot Servo Drum - Frozen SDR submitted: The aeroplane was parked outside overnight in the rain. The following day while flying at FL240 (24 000 feet) the pilot received an auto-pilot (A/P) “disconnect” annunciation. The pilot then manually took control and noted a slight resistance of the elevator control inputs.
Prior to next flight, maintenance personnel gained access to the tail section and found the elevator auto pilot servo cable drum coated with ice. It was apparent that the rain (the previous night) had drained down onto the stabilizer and then migrated onto the cable drum. During flight the next day at 24 000 feet, ice formed on the A/P cable drum and caused resistance of the elevator controls. The operator stated that this was the 2nd occurrence of this nature. Transport Canada Comments: Transport Canada Civil Aviation wish to remind owners and operators to hangar their aeroplane (whenever possible) during rainy conditions. Any interference of the primary or secondary flight controls can jeopardize the safety of the flight. SDR # 6 Engine High Pressure Fuel Leak SDR submitted: The pilot noticed a fuel leak during preflight inspection.
Maintenance personnel removed the engine cowling and cleaned the residual fuel from the immediate area. When the engine was being run-up to check for fuel leaks, it was then noted that a high-pressure fuel spray was coming from a fuel line that attaches from the engine pylon area to the hydromechanical fuel unit. The fuel spray was contacting the back of one of the engine igniters. Fortunately, the engine was immediately shutdown without a major fire. The defective fuel line was replaced, however there was no chafing or wear damage evident. Transport Canada Comments: A search of the SDR database revealed several previous reports of this engine motive fuel line being chaffed and damaged by contacting the adjacent cowl latch.
The power plant installed on this aeroplane has tight clearances; therefore it is recommended that adequate distance between lines, tubings, cables and wires be adhered to. SDR # 9 Cargo Door Hydraulic Leak SDR submitted: A hydraulic fluid leak was identified when closing the main cargo door. Maintenance investigation identified hydraulic fluid leaking from the cargo door manifold assembly at the check-valve body due to a circumferential and through crack. The manifold assembly was replaced, a leak and function check carried out and the aircraft was made serviceable.
Transport Canada Comments: The check-valve cylindrical body, which is mounted to the manifold assembly, has two “Hex wrenching” flat surfaces. One near its base used specifically to mount it to the manifold and a second one at the attachment of the hydraulic line, used for line attachment support. It is suspected that the hydraulic line was torque during installation without the use and support of the check-valves Hex wrenching surface, stressing its cylindrical body and causing its failure. Transport Canada Civil Aviation (TCCA) would like to advise all maintainers the importance in understanding these design features and maintenance practices for the correct installation of hydraulic components. SDR # 3 CFM56-7B Engine Check Valve Failure SDR submitted: During descent with the auto-throttle (a/t) engaged, the flight crew encountered a left engine surge and intermittent stalls. The crew disengaged the a/t and using manual throttle inputs, were able to sufficiently control the engines tendency to surge. The engines parameters remained normal during descent and made an uneventful landing.
During maintenance taxi to the hangar, the left engine fuel flow was fluctuating slowly between 700 and 800 lbs/hr. When the thrust levers were advanced slightly, the left engine started to shake and vibrate with subsequent annunciation of an engine fail message and an automatic engine shut down occurred. Maintenance personnel accomplished FIM 71-05 task 805 and subsequently found the 5th stage compressor check valve stuck open. The valve was replaced as the corrective action and the aeroplane was returned to service. Transport Canada Comments: It is important for maintenance personnel to recognize the characteristics of a failed engine compressor check valve to prevent further engine surging.
SDR # 1 Slat Drive Shaft Loose Screws SDR submitted: While removing the right engine pylon during a scheduled event, maintenance found a left-hand wing leading edge flap drive shaft coupling sleeve, at wing station 468, with loose attaching screws due to missing lockwire. The attaching screws were re-torqued and lockwired as per Aircraft Maintenance Manual (AMM) 27-81-05 & 27-52-09. Upon this finding, the operator proceeded to inspect its remaining Boeing 747 fleet of all leading edge flap drive shaft couplings and trailing edge flap torque tube couplings to ensure for proper installation and safety in accordance with the AMM. Transport Canada Comments: All aeroplane attaching hardware incorporate a form of lock or safety to ensure that the applied torque is kept through the life of the fasteners installation.
Lockwire is one of several methods used to perform this important and essential function. SDR # 5 Pylon Panel Missing SDR submitted: On arrival after a flight, it was noticed that inspection panel 443BR on the outboard side of the right engine pylon was missing. Panel part number (P/N) 311n5049-139, IPC 54-53-01-05, item 175. The panel was replaced and the aeroplane was made serviceable.
Transport Canada Comments: A similar event had occurred previously with this operator and an internal investigation was done through their standard Safety Management System (SMS) process. The results defined the root cause of the events as being induced through the improper installation of the panel. Boeing AMM 54-53-01 defines the correct panel “latch indicator groove” alignment as seen below for a “closed/locked” and “open/unlocked” position. Also included is a picture of the backside of the panel as seen in the “closed/locked” position. Note that the “groove indicator” marks are a direct indication of the rotating latch position which retains the panel to the pylon structure.
SDR # 4 Global Express Secondary Power Center Stud Burn SDR submitted: The flight crew reported that the multi-functional display (MFD) unit 1 went blank. APU would not start and after engine start, “DCU A OFF”, Flaps Fail, Fire Sys. Fault, Inboard Brakes Fail, L/H IAPS Fail, Pack Fail, Cabin Pressure Fault, FDR Fail, R/H Eng.
Thrust Fault, R/H Eng. Fault, RDC Fault and MFD XTALK Fail messages appeared. MFD 1 and 2 swapped and the failure condition remained on the same side. There were no electrical fault CAS messages except for the DAU A circuit-breaker (CB) had tripped. Two bus bars (ESS bus) were confirmed with no power and the battery connections were verified all good. On visual inspection of the L/H Secondary Power Center (SPC), the T1 wire-lead and stud was confirmed as badly burnt and melted.
The SPC was replaced and the aeroplane was made serviceable. Transport Canada Comments: Electrical faults are difficult to trouble-shoot and identify due to the system complexity and, as in this case, multiple cascading fault messages can be generated. Wiring stud torque values are essential for the continuous and correct operations of all electrical systems. Transport Canada Civil Aviation (TCCA) would like to emphasize to all operators and maintainers, the importance of correct wiring installation torque values of wire lead stud attachment points. SDR # 1 Global Express NLG Trunion End-Cap O-Ring Pinched SDR submitted: During an unscheduled maintenance task, a technician noticed grease migrating into the nose fuselage underfloor area, between fuselage station (FS) 202 and 280, from a nose landing gear trunnion bearing end-cap. Maintenance investigation revealed that the bearing caps recessed O-ring was improperly installed and found pinched, allowing grease to ingress into the pressurized nose fuselage underfloor area. The O-ring was replaced and correctly installed; cap reinstalled per AMM and the aeroplane was made serviceable.
Transport Canada Comments: Grease in that area is potentially dangerous because of the close proximity of four oxygen bottles therefore Bombardier Aerospace has issued advisory wire AW7, defining this possible scenario and corrective action. Transport Canada Civil Aviation would like to advise all BD700 operators of this event and of the advisory wire instructions issued by Bombardier. SDR # 5 Spoiler Power Control Unit Harness Clamp Chaffing SDR submitted: While carrying out a planned maintenance inspection task of the flap system, it was noticed that the flap drive torque-tube located directly under the right-wing inboard flight spoiler power control unit (PCU) was rubbing on a harness p-clamp when the flaps were transitioning from zero to eight degrees and back. The p-clamp was determined to be incorrectly installed and was repositioned 180 degrees in a pointing up position to provide the required clearance. Transport Canada Comments: There are 4 multi function spoiler PCU’s on the aeroplane. The Aircraft Maintenance Manual (AMM) outlines the procedure specifically for the installation of the 4 different PCU’s. Presently in the AMM, there is no mention of the required p-clamp positioning that secures the wiring harnesses of the PCU’s.
Transport Canada Civil Aviation (TCCA) is presently working with Bombardier Aerospace to address this issue. TCCA advises all operators of this possible PCU harness configuration discrepancy. SDR # 5 Flap Transmission Support Bracket – Cracked/Dislodged SDR submitted: Uncommanded flap retraction from 20 degrees to 10 degrees during approach resulted in a drop of 50 feet. Shortly thereafter, the flap motor circuit breaker popped.
Following an uneventful landing; maintenance personnel found that the flap transmission support bracket had buckled and twisted, thereby pulling the flap transmission out of position. Cessna Caravan Service Bulletin CAB05-4 (4 April 2005) titled “Flap Actuator Support Bracket Inspection/Replacement” had been complied with, on 28 August 2005, at TSN 6959 airframe hours. CAB instructions are to inspect for cracks along the inboard and outboard flange radius on the forward and aft areas of the support bracket. The operator then carried out Cessna Service Kit (SK) 208-158 to replace the support bracket.
Transport Canada Comments: The flap transmission brackets absorb significant air loads when the flaps are deployed; therefore it is important that the crew ensures that flap limitations/airspeeds are followed in accordance with the Pilots Operating Handbook. A loss of lift during a critical phase of flight (approach) can greatly reduce the level of flight safety. It is also recommended that maintenance personnel pay particular attention to the inspection of this flap bracket area.
SDR # 1 Elevator Trim Actuator – Freeze Up SDR submitted: During cruise flight with autopilot engaged, the cockpit Advisory Message indicated “Mistrim Nose Dn”. The pilot disengaged the autopilot and then noted that additional forward control column force was required to maintain level flight.
The pilot was unable to move the elevator trim forward because the trim wheel was jammed. The trim indicator also indicated a position forward of the take-off range. It was also determined that the elevator trim would move rearwards but not forward. Following an emergency declaration to ground control, the crew conducted a normal approach and uneventful landing. Maintenance personnel carried out a functional check of the elevator trim system but were unable to duplicate the reported condition. Further examination revealed that the elevator trim screw jack assembly lubricant appeared to be milky in color with some water visibly present.
Both the L/H and R/H screwjack assemblies were then purged of all contaminated grease/water and lubricated in accordance with the manufacturers’ instructions. Prior to this flight, the aeroplane had been parked outside in heavy rain, which may have resulted in a buildup of water in the screw jack actuator cavity. By the time the aeroplane reached cruising altitude, ice had formed and restricted elevator trim movement. It appears that ice had clogged the trim actuator chain links preventing trim movement. Additionally, one of the tail plane access holes was not properly sealed thus permitting water to migrate into this aresa. Transport Canada Comments: A review of the SDR database revealed two similar reports related to water ingress and “freeze up” of the trim actuator chain link mechanism. Operators are reminded to be cognizant of these hazards in inclement weather.
SDR # 7 Hydraulic Lines Swapped SDR submitted: After a series of flights and daily inspections, maintenance engineers noticed a slow transfer of hydraulic fluid between the left and right hydraulic systems. Detailed inspection of past maintenance activities was initiated in conjunction with recommendations from the manufacturer. The left aileron servo actuator hydraulic system return lines were found to be interchanged. The left system pressure was returning to the right system hydraulic reservoir and vise-versa for the right system pressure.
The lines were returned to their correct positions and the aeroplane was released for service with a monitor for close hydraulic system reservoir level checks. After several flights it was noted that the fluid transfer continued yet significantly reduced.
Further maintenance inspections discovered that the right aileron servo actuator system return lines had also been interchanged. The lines were reconfigured in their correct positions, the aeroplane was made serviceable and after several flights it was confirmed that the fluid transfer had stopped. Transport Canada Comments: Correct hydraulic line configurations are essential for proper aeroplane hydraulic system operations.
The Aircraft Maintenance Manual (AMM) chapter 27-10-80 contains a “note” specific to the above scenario defining the correct hydraulic line installation configuration. In correlation with the Fault Isolation Manual (FIM), the AMM should also be used to confirm correct system operation and installation when trouble-shooting a snag. SDR # 4 Engine Mount Cracks SDR submitted: Upon a routine servicing, maintenance found the L/H lower engine mount tubular frame to be cracked through on both of the inboard and outboard areas. The engine mount was removed and sent for repair. Transport Canada Comments: A similar event occurred to the same operator on another aeroplane where Transport Canada Civil Aviation (TCCA) advised M7 Aerospace, the manufacturer and type certificate holder of the aeroplane, along with the Federal Aviation Authority (FAA).
TCCA would like to advise all operators that M7 Aerospace have recently issued Service Bulletin 226-71-018 for a detailed inspection of the concerned engine mount area.
Quoting : G'day GFA330, Many factors are involved in corrosion forming in commercial aircraft. Significant factors include the environment the aircraft is flown in, spillage of any corrosive cargo, and age. Generally speaking, older aircraft will have more corrosion than newer ones.
'D' checks are usually where comprehensive corrosion checks are performed. Newer aircraft in for their first 'D' check may have little or no corrosion, whilst older aircraft in for their third or fourth 'D' check may have much more corrosion. Corrosion checks usually become more thorough as the aircraft ages and the rectification of this corrosion can add many weeks to the length of a 'D' check. Corrosion is not really a problem if it is caught in time and rectified. When corrosion is found, it is usually removed by grinding with a sandpaper wheel on a die grinder.
It is essential to remove all the corrosion and smoothly blend the area where it has been removed into the surrounding structure. Measurements of the blend-out are then taken and compared with the limits in the Structural Repair Manual (SRM). If the blend-out is within the SRM limits, the area is treated with iridite.
Iridite is a two part chemical process that firstly cleans the aluminium by acid etching the surface. A special chemical layer is then applied to this surface which forms a protective layer on the bare aluminium. When dry, the surface is primed and painted. There are other chemical corrosion protection kits for magnesium alloys. I'm not to sure about titanium alloys.
If the corrosion is outside the SRM limits, you generally have two choices. If it is particularly severe, the easiest option is to generally replace the damaged structure with a new component. The SRM may also suggest repairs to re-inforce parts of the structure when it may be difficult and time-consuming to replace structure. In the end, it is the cost and time to inspect for and repair corrosion damaged structure that may signify the 'economical' end of an airliners life.
Regards, JetMech. My experience is with light aircraft, and corrosion is second only to damage as a reason for ending a light aircraft's life. From an engineering perspective corrosion presents two problems: first, of course by reducing the effective thickness of the metal, and second by creating stress concentration points that can lead to cracks. This is particulary important for structural members like wing spars, where a seemingly insignificant amount of corrosion may in fact be a big deal because of the likelyhood that it can induce a crack. Corrosion protection is only as good as the mechanic applying it, as jet mech says, you must remove ALL corrosion first, it is no good leaving a bit to keep within limtis because your problem will only come back. Iridite is a strange trade name? Ive known and have only ever used Alocrom 1200 to reprotect, this has 2 parts and is a 50:50 mix, you should neutralise with water after application then clean the area.
Most common areas for corrosion on pax a/c will be the floor structure under toilets and galleys, any dissimilar metal contact such as behind steel anchor nuts are a favourite, steel with aluminium placed in an electrolyte equals corrosion. If you take a screw out of a floorboard and white dust comes out with it, this generally means your going to lift the boards up to find a whole load of overtime coming your way. Boeing generally have repair schemes In accordance with the SRM for most floor structure, but airbus generally have a 'Meccano' assembly, unbolt corroded structure, place new piece in, drill off new piece and hi lok or bolt it in. Most aircraft flying round will have corrosion on them, the extent depends on the age and QUALITY of maintenance carried out. Best regds a/c. Quoting : Many factors are involved in corrosion forming in commercial aircraft. Significant factors include the environment the aircraft is flown in, spillage of any corrosive cargo, and age.
Generally speaking, older aircraft will have more corrosion than newer ones. 'D' checks are usually where comprehensive corrosion checks are performed. Newer aircraft in for their first 'D' check may have little or no corrosion, whilst older aircraft in for their third or fourth 'D' check may have much more corrosion. Corrosion checks usually become more thorough as the aircraft ages and the rectification of this corrosion can add many weeks to the length of a 'D' check.
Corrosion is not really a problem if it is caught in time and rectified. When corrosion is found, it is usually removed by grinding with a sandpaper wheel on a die grinder. It is essential to remove all the corrosion and smoothly blend the area where it has been removed into the surrounding structure. Measurements of the blend-out are then taken and compared with the limits in the Structural Repair Manual (SRM). If the blend-out is within the SRM limits, the area is treated with iridite.
Iridite is a two part chemical process that firstly cleans the aluminium by acid etching the surface. A special chemical layer is then applied to this surface which forms a protective layer on the bare aluminium. When dry, the surface is primed and painted. There are other chemical corrosion protection kits for magnesium alloys.
Airbus A321 Maintenance Manuals
I'm not to sure about titanium alloys. If the corrosion is outside the SRM limits, you generally have two choices. If it is particularly severe, the easiest option is to generally replace the damaged structure with a new component. The SRM may also suggest repairs to re-inforce parts of the structure when it may be difficult and time-consuming to replace structure. In the end, it is the cost and time to inspect for and repair corrosion damaged structure that may signify the 'economical' end of an airliners life. Regards, JetMech Very well said JetMech,another thing that can prevent the onset of corrosion, is by applying a corrosion prevention compound to the airframe.The amount and frequency it is applied, is up to individual operators and what enviroment the aircraft is flying in.I know that Air NZ applies a huge amount of CP to their aircraft due to the operating enviroment that they fly in, consequently Air NZ aircraft are usually corrosion free. Guys, I'm guessing y'all have never done a tank and plank job, because where the bad stuff is, is inside of fuel tanks.
See, where there's entrained water in fuel, bacteria live at the interface, eat the fuel and crap in the water.which is corrosive indeed. Biocides are used to some effect but not always effective. Matter of fact, I proved this again the other day when the power went out.Pulled a kerosene lamp down off the shelf to get it ready and refill it and it stank. The fuel, which is colorless (I use mineral spirits because it's cheap) had turned a piss yellow, there was a little disk of crap in the bottom of the glass and it smelled awful. Cleaning the lamp out with anhydrous isopropyl cleaned it all out.had the lamp been metal it would have rotted the bottom out of it. Quoting : How common is that corossion is found on commercial acft?
Is this a sign that the aircraft is nearing the end of it's life? Corrosion is very-very common in aircraft, but that is why airlines and airplanes have routine inspections and checks. To look for and repair defective areas. Corrosion prone areas include: entry areas, galley under floor, under lavs areas and under cargo areas. Many of these areas will get a special treatment of CPC (Corrosion Preventitve Compound) to help extend the life in these areas.
Manual 2tr-fe. Quoting : Iridite is a strange trade name? Ive known and have only ever used Alocrom 1200 to reprotect, this has 2 parts and is a 50:50 mix, you should neutralise with water after application then clean the area.
I'm not sure of the actual name of the chemicals, but we used to call it an iridite kit for whatever reason, and I did get the details of the process a bit wrong. The first chemical to be applied to the bare aluminium is the cleaning chemical.
You then use scotchbrite to scrub the surface thoroughly. Scotchbrite is the tradename for the polymer based scouring pads used to clean pots and pans. Once you have scrubbed thoroughly, you rinse with water as you mentioned. I used to then repeat the cleaning process once or twice more to get the surface as clean as possible.
Once the surface is clean, you spray the etching / protective chemical on, usually while the surface is still wet from the last rinse. You are meant to leave the etch / protective chemical on until you get a light golden brown colour. You then rinse the excess off with water which leaves the surface ready for primer and paint. Quoting : is by applying a corrosion prevention compound to the airframe Yep, I completely forgot about that. We used to use a two part spray on chemical process made by the Ardrox company. The first coat was light Ardrox which was a light water repellent oil. Once this was dry, we would apply heavy Ardrox which used to spray out as a light to medium foam.
During my later days at my first employer, Boeing began to use a one part CPC, which appeared bright red on the surface like a mix of blood and tomato sauce! The worst thing after a day spent CPC spraying was all the excess CPC chemicals that fell on you. You would try to wash your hair when you got home but you would find that all the CPC had completely water proofed your hair! Regards, JetMech. Quoting : How common is that corossion is found on commercial acft?
Also, I'd like to ask how common it is to find corossion inside the engines (both piston & jet) of aircraft. After taking some shots of this Challenger bizjet, I looked in the rear section of one of the engines and was surprised to see a patch of rust. At least it looked like rust at first because of the colour.
Then I believed that it was a stain from some kind of liquid. In the case of a jet engine, can areas of rust appear in the exhaust nozzle if the aircraft has just sat around for a while & the engines haven't been started? If the answer is yes, how big of a concern would it be & would it need to be fixed or would the hot jet exhaust just burn it away after the next engine startup?
Thanks, Chris. Quoting : Also, I'd like to ask how common it is to find corossion inside the engines (both piston & jet) of aircraft. I don't have enough experience with turbine engines, but I do know that piston engines can be prone to corrosion on the cylinder walls if the engine sits unused for a long period of time. If you are going to have a piston aircraft sit unused for an extended period of time, you need to accomplish certain preservations steps (i.e.
Use preservation oil and desicant plugs) to protect the engine. Being a structures type, I have seen some significant corrosion damage. I saw a 737 not too long ago that had a good portion of the bear strap around the aft cargo door just flake away. Anyone that knows the door cutout repairs for the 737 will tell you that they are not fun. You almost expect that the aircraft will list to the right with the amount of weight you are adding!
Quoting : Corrosion is very-very common in aircraft, but that is why airlines and airplanes have routine inspections and checks. To look for and repair defective areas. Corrosion prone areas include: entry areas, galley under floor, under lavs areas and under cargo areas.
Many of these areas will get a special treatment of CPC (Corrosion Preventitve Compound) to help extend the life in these areas. Back in the day Garrett was outfitting B727s for rich Arabs on a regular basis. They got a couple from Qantas, and I gotta tell you-the Aussies had about tbe best damn anti corrosion program around. EVERYTHING had a good thick coat of LPS on it. As far as engine corrosion I did my share of repairs to the same on Garretts which used a magnesium engine case.
What we'd have to do is wire brush the paint and corroded metal off, treat with Dow-19 (buffered chromic acid solution) prime and paint. Sometimes we'd rebuild the metal surface with DEVCON which is the best damn epoxy stuff around. Forgot to mention one of the worst I ever saw, it was a 707-138B that belonged to Frederick B. Ayer in New York and had been leased to Bouraq for the Hajj run in Indonesia. Well, Bouraq hadn't paid their fuel bill so Shell deadlined the aircraft and it sat on the ramp in Indonesia for a couple years. Anyway, something got worked out and a crew brought it back to the states.
It hit the coast 75 miles off course and got the people at Vanedberg up in arms. It sat on the ramp for a few weeks so I got on board thru the door behind the nose gear. The upstairs crapper had leaked and corroded all the radios underneath it.
The rest of the airplane smelled like a barn. It still had the sextant and the port hadn't been plugged. That's part of why they hit the coast 75 miles off course. Speaking of smell, the worst airplane I ever was on was a Jetstar that belonged to Coca Cola, then got sold to Ferdie and Imelda Marcos. It sat on the ramp for a couple years in the Phillipines, but before it got closed up, the cabin crew all took dumps in the chemical toilet. It got bought by Tiger Air and the crew flew it to Los Angeles with a case of Ozium-every fifteen minutes they'd spary a can in the cabin and then retreat to the cockpit. Tiger Air ended up selling it to somebody who had to tear out all the interior because the smell had soaked into the vinyl and insulation and couldn't be removed.
Dl a few years ago switched to Cor-Ban made by Zip-Chem Products. It is a lot easier to apply than the old brown stuff we used to use.
I can't recall the proper name for the old stuff. Cor-Ban comes in an aerosol can that can be directed into the toughest spots.
As for the original question about corrosion. Yes, it is out there.
I worked structures for 8 years in DL heavy check. Spent a lot of time on MD88, 727 and 737 classics. Number one spot to find it on any airplane is under the lav and galley. I didn't do much work in these areas. Most of my time was bagbins and wings.
I think the worse place I consistantly saw a lot was in the back end of the 737. Between the lav valve and the out flow valve there is a lot of mositure behind the aft bulkhead. Sometimes it seemed that everything we touched in that area just turned to dust. The MD88 bagbins also get quite a bit of work.
The door thresholds are usually pretty beat as well as most of the belly frames aft of the aft bin door. Both of these items usually occured by the second overhaul and could be saved by blending out the corrosion.
By the third overhaul they were either repaired or just outright replaced. The cargo tie down tracks and seat tracks in the cabin are another spot.
The seat tracks I think ususally were saved, but we found it cheaper to just replace the cargo tracks. Why waste three shifts grinding only to find it out of limits when it can be replaced in four hours. We never really found much corrosion in the wing tanks. Most of the tank work I did was leak related. Quoting : Quoting Mr Spaceman (Reply 10): Also, I'd like to ask how common it is to find corossion inside the engines (both piston & jet) of aircraft.
I don't have enough experience with turbine engines, but I do know that piston engines can be prone to corrosion on the cylinder walls if the engine sits unused for a long period of time. PurdueAv2003, Thanks for your reply & your answer. I've seen how car engines can get eaten away by corrosion when the car's been abandoned in a junk yard. That's a complete mess. Regarding turbine engines, does anyone know what the discolouration in the tailpipe of the jet engine in my photo above is likey caused from? If it's not a rusty spot of corrosion then what would that brown stuff be in there? Thanks, Chris.
Just a minor correction to Jetmech's post. It's not only on D checks that comprehensive corrosion detection is done. Where I work, we are not certified to do D checks, only up to C.
We do an extensive CPCP programme on the B757. Our fleet includes the B757 that is the world leader in terms of cycles - oh and it's just turned 24 years old (date of build was 1 March 1983). I'm not sure where they send them for the D check's though. I have seen some 2-3 year old A320's come in and have to have every single seat track under the wet areas changed - have yet to see a B757 that bad. Quoting : Guys, I'm guessing y'all have never done a tank and plank job, because where the bad stuff is, is inside of fuel tanks. See, where there's entrained water in fuel, bacteria live at the interface, eat the fuel and crap in the water.which is corrosive indeed.
Biocides are used to some effect but not always effective. I have never encountered corrosion inside fuel tanks on modern jets, though I have to say at the same time that I have never found water in the fuel samples taken during weekly checks either.
I assume that noadays the water scavenging systems are so good that if a plane is regularly used (the fuel not standing in the tank for a prolonged time, like aircraft in storage), there is not enough water to promte corrosion. Quoting : Back in the day Garrett was outfitting B727s for rich Arabs on a regular basis. They got a couple from Qantas, and I gotta tell you-the Aussies had about tbe best damn anti corrosion program around.
EVERYTHING had a good thick coat of LPS on it. Quoting : Anyone use LPS3 + Danitrol. Regds MEL Personally I don't like LPS3 too much, because it will stay sticky and attract dirt. I prefer Dinitrol AV-8, AV-30 etc., because after a few days the surface becomes dry enough to touch (with the protective coating still being elastic to follow movements of the metal, similar to a layer of wax), so that dust and dirt will not stick on it. Quoting : have never encountered corrosion inside fuel tanks on modern jets, though I have to say at the same time that I have never found water in the fuel samples taken during weekly checks either. I assume that noadays the water scavenging systems are so good that if a plane is regularly used (the fuel not standing in the tank for a prolonged time, like aircraft in storage), there is not enough water to promte corrosion.
Kind of depends on how new the aircraft is and where it's being operated and who's supplying the fuel and how long it sits on the ramp between trips, right? Never say never.I've been in on a few tank and plank inspections and I've seen the stuff. Seen a few aircraft scrapped because the wing planks were corroded past serviceable limits too. Quoting : Quoting PurdueAv2003 (Reply 12): I don't have enough experience with turbine engines Turbine engines have terrible corrosion. It was very rare that on every heavy engine visit we did not have to scrap one or more disks due to corrosion.
Airbus A320 Manual
This usually occured on the HPC module in most cases. I know on the JT8D there is AD 2003-12-07 that mandates a 7 year corrosion inspection and NICAD re plating on the date regardless of the cycles or hours on the disk. Greasy, that sounds kind of type and manufacturer specific. We never did that on Garretts as the wheels were solid Inconel and the impellers were solid titanium.
Airbus Maintenance Manuals
Matter of fact, the slickest repair I ever saw was one I worked on that had taken a seagull and actually bent one of the impeller blades. It still ran but sounded funny.
It's a titanium forging and it takes a lot to bend a blade-only one I ever saw. We sent the impeller to Garrett and they sliced the blade down and welded a new chunk on and reprofiled it-you could hardly tell it had been repaired. How's the academy going? Every type from fighters to helicopters from air forces around the globe Props and jets from the good old days Views from inside the cockpit Passenger cabin shots showing seat arrangements as well as cargo aircraft interior Pictures of great freighter aircraft Aircraft flying government officials Our large helicopter section.
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