PIA Airbus A310 makes emergency landing at Karachi Airport

[FMC]

Well, if you live to tell your story it is a safe landing. PIA pilots are heavily overpaid and trained to handle such abnormalities. Instead of praising the pilots we should question the 'new credibility' of PIA Engineering.
And BTW the Quality Assurance deptt is headed by a senior active pilot. Furthermore, the QC also reports to the QA. Now the question is why was AP-BDZ allowed to take to the air without the NDT cosequential to a near fatal incident a couple of months back.
PIA wallas must get their acts together and curtail the PKR 3 crore /month financial loss being incurred by the state carrier.

[FULLTHRUST]

PIA pilots are heavily overpaid and trained to handle such abnormalities

there is no corelation in between salaries and training!!!. what are you trying to say? please explain.

[FMC]

Overpaid by pakistani standards. Training expenses as borne by PIA. A major chunk of Flight operations budget is eaten up by the training and manuals section. The airline therefore expects its pilots to deliver as recommended by the aircraft manufacturer. As a comparison take a ride in the locomotive cab of a night train from Khanewal to Rohri or v/v.

[ConnieMan]

Overpaid by pakistani standards. Training expenses as borne by PIA. A major chunk of Flight operations budget is eaten up by the training and manuals section. The airline therefore expects its pilots to deliver as recommended by the aircraft manufacturer. As a comparison take a ride in the locomotive cab of a night train from Khanewal to Rohri or v/v.

Sorry but senseless observation mate!...

[FMC]

I do not think that my observation is senseless. PIA should have bought the B777 FFS alongwith the order for 8 B777s. The cost of training the crew abroad is exhorbitant. Same was the case with the A310 FFS. It was installed a year ago when this plane now is in the [process of being phased out. My contention is that PIA's flight training wing books the simulator slots abroad according to the whims of their pilots rather than the economics. Save today for a better tomorrow.

[INSIDER]

Dear FMC

Well i am not sure what to say to you, so 5 words for you:

Your post is not making any sense.........if you dont know the working of an airline then please stay quiet.

Would you please elaborate your senseless observation and give me a proof that simulator slots abroad are book according to the whims of their pilots and can you please tell me what is the cost of of FFS and the A310 simulator in KHI is it working properly................

PIA pilots underpaid and overloaded with work. You are one of those people who think that pilots are sitting and doing nothing and auto pilot is doing the job and the crew is having a best meal of his life...........

[Abbas Ali]

PIA Airbus A310-308 (registration AP-BDZ) on a pre-delivery test flight over France in 1991. AP-BDZ was PIA's very first A310.

Aircraft Type: Airbus A310-308
Registration: AP-BDZ
Manufacturer's Serial Number (MSN): 585
First Flight: March 18, 1991
Delivery to PIA: June 25, 1991

From a friend, I received a copy of February 8, 2007 report prepared by Goodrich for Airbus Industrie. According to this report PIA Airbus A310-308 (registration AP-BDZ) experienced two events in January 2007 which were attributed to the failure of a Model 0851HV Pitot probe.

Here are extracts from the report.

Background:

PIA experienced two events in January 2007 which were originally attributed to the failure of a Model 0851HV Pitot probe. Airbus asked Goodrich Sensors and Integrated Systems (GSIS) to fully examine the removed Pitot probe from PIA, to determine failure mode and to report any correlation between the probe condition and PIA's January events.

Information Provided:

Information received by GSIS from Airbus on January 16 is indicated below:

"The MSN 585 (Airbus A310-308 - AP-BDZ) has experienced two CAS drop events in cruise, one in late November (causing serious impacts on aircraft navigability and structure) and one in early January (no impact).
We suspect severe icing conditions which have prevented from a correct pt measurement during several seconds or several minutes. But we want to check that this Pitot is correctly operating with the right power consumption.

The CAPT Pitot probe has the following SN: 213667.

PIA will send the unit to GSS in Burnsville soon.

So, please, GSS to provide Airbus Industrie with an investigation report on this unit by February 2nd."

Attached were the PIA conditions at the time of the events. This information was invaluable to GSIS for finding the correlating the failure mode to the events noted by PIA's pilots.

Event 1:

Jan. 8, 2007 Flt PK-315 (Lahore to Karachi).
Aircraft in climb with an altitude of 28,000 feet.
API is engaged (ATHR mode not recorded.)
The Mach starts to increase from 0.815 to reach a maximum of 0.83.
MMO warning for this aircraft type is 0.84 and is not activated.

Event 2:

Jan 11, 2007 Flt PK-743 (Islamabad-Lahore-Riyadh).
Aircraft in cruise at FL 340.
AP2 is engaged.
Mach 0.79 & CAS 275 kt
Around GMT 17:39 abrupt speed variation between 275kt to 75kt during 10 minutes.
ATHR reacts to the speed movement by thrust variation (AP2 remains engaged)
MMO warning for this aircraft type is 0.84 and is not activated.

The information from Airbus notes two events, one in "late November", the other in "early January". GSS does not have information from any November event, but did receive information on the two events mentioned, both having taken place three days apart in early January. This discrepancy did not hamper our analysis or findings.

Initial lnvestigation:

This particular 0851HV Pitot probe was manufactured May 1, 2002. Hence it is 21 months past its three year warranty expiration, so has provided good, long service to PIA since new.

Model 0851 HV SIN 213667 was received by GSIS the evening of January 25, 2007 and was examined the very next morning by our FAA-certified service center technician.

The exterior of the probe's sensing head was in good condition with very little corrosion due to the electroless nickel plating.

It was immediately evident upon initial heater tests however, that the heater was damaged. The unit was transferred to the GSIS Product Improvement Lab (PIL) for a detailed analysis to root cause.

Detailed Investigation:

The PIL issued Report #8346 on February 8, 2007 containing its findings.

The PIL reported evidence that the heater element sheath was severely corroded in the probe's "nose" (just inside the Pitot inlet) leading to moisture and contamination getting into the heater insulation. Eventually, this caused dielectric breakdown to occur. When this occurred the heater wire melted, opening the wire. Subsequently both sides of the open were shorted to the case by the molten material. Thus, the circuit as measured at the connector pins still had continuity. However, it did not have the proper resistance, and likely only a portion of the heater would have been functional - from the voltage input connector pin up to the short.

While corrosion of the heater sheath after extended lifetime is a common wear-out mode, it is not common that both sides of the open short to the case, which is required for the circuit to still have continuity. Opens along with shorts do happen occasionally, but usually there would only be one side shorted. Also, sometimes the open may short, but the short is high resistance (kilo-ohms, or megaohms). This probe had both sides short and they were both low resistance. This could explain why the probe might not de-ice properly yet not annunciate a failure in the cockpit.

Regarding failure annunciation in the cockpit, the failed probe would have still been drawing current, but likely a different current than what is normal. If a current monitor is used to check for heater failure (which is typically how it would be done), it may or may not have detected this failure depending on what the current limits are set at.

Even if a failed heater that fused open only had one side of the open short to case, it could possibly still draw current (depending on which side is shorted) but the continuity would read open when tested at the connector pins. Thus, an open and single-side short could cause an undetected failure when using a current monitor to detect failure.

This PIA failure still had continuity at the pins, but it's likely the failure was undetected because the probe was still drawing current (not because it had continuity). GSIS is not sure but does not think a continuity check is the method used for failure detection in service.

Tie Between Failure Mode and Events #1 and #2:

Mach number is a function of Pt/Ps.

Event #1 was represented as an apparent increase in Mach not attributed to intentional aircraft acceleration, and which happened during an increase in altitude. If the heater had already failed (as described above) and the aircraft was in icing conditions, the increase in Mach would likely be attributed to an unchanging Pt (caused by icing of the probe's drain holes and aft onto the strut). The decreasing Ps due to increasing altitude would alter the ratio of Pt/Ps such that Mach would appear to increase.

Event #2, 3 days following Event #1, was represented by a significant apparent decrease in velocity during a 10-minute span of time not attributed to intentional deceleration. In this case and in icing conditions again, were the Pitot inlet to ice up due to heater degradation, the probe's drain holes remained open, and the static pressure remained even (not in climb or descent), then the Mach number would appear to decrease due to the same function of Pt/Ps, and the indicated airspeed would appear to decrease due to the function pt - Ps. In this case, the Ps remained the same, while the pt slowly decreased towards the Ps pressure due to its iced up conditions.

Commonalitv of this Wear-Out Mode:

Corrosion through the heater sheath near the Pitot inlet and resulting dielectric breakdown causing heater failure is a standard wear-out mode of Pitot probes. The sulfur and chlorine components of the corrosion are common to this nickel material in standard aviation (flight) environments. The failure mode described in which both ends of the separated heater element become welded to the case and thus maintain continuity is not common, and further is characteristic only on 28 VDC systems (not 115 VAC systems). In this event the heater element separates and welds its ends to the case, the continuity along the heater element remains, but not all of the current flows through the heater element. Some of it flows through the probe and returns to the source via the aircraft structure. Since less power is dissipated within the probe, it will not be sufficiently anti-iced and can cause events like those described by PIA. Also, the circuit resistance change following this kind of failure on a 28 VDC system is small and the current usually remains within the expected circuit limits. (On the other hand if a failure like this occurs on a 115 VAC probe, the circuit resistance change is very large and the current almost always exceeds the expected high limit. Many times the remaining portion of the heater element will simply burn out before say a circuit breaker is tripped because it cannot handle the large increase in current. In either case this heater failure will be detected.)

Summary:

Model 0851HV S/N 213667 has provided nearly five years of service. The failure mode in which the heater sheath corrodes and admits moisture is a normal wear-out mode. In this case on a 28 VDC probe, the element, once broken, welded itself to the case. This provided continuity, some probe heat, but insufficient heat to achieve proper and total anti-icing capability. Thus, in two separate events, the probe caused Mach changes consistent with partial-icing conditions caused by the heater element failure, and consistent with the mathematical foundation of Mach measurement.

Here are some photos of Model 0851HV Pitot probe removed from PIA Airbus A310-308 (AP-BDZ) and received by GSIS the evening of January 25, 2007.


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[inducedrag]

A very interesting report good work ABBAS

[ConnieMan]

Abbas Bahi thanks for indept reports on this incident, its very interesting to know what caused such failures, do you have any analysis with these reports also?

[F.K]

who was the captain?

[FMC]

Dear FMC

Well i am not sure what to say to you, so 5 words for you:

Your post is not making any sense.........if you dont know the working of an airline then please stay quiet.

Would you please elaborate your senseless observation and give me a proof that simulator slots abroad are book according to the whims of their pilots and can you please tell me what is the cost of of FFS and the A310 simulator in KHI is it working properly................

PIA pilots underpaid and overloaded with work. You are one of those people who think that pilots are sitting and doing nothing and auto pilot is doing the job and the crew is having a best meal of his life...........

Back in 2004 Rashid Hassan had briefed the Senate Standing Committee on Defence that the 8 B777s will be completely paid off in 25 years and this was also carried by the national press. The cost of crew transition and recurrent training abroad is making a very big dent in PIA's finances . B777 operation is incurring huge losses due to the MARK UP payments. Add to it the above mentioned training costs for 25 years. The calculator runs out of digits.

[inducedrag]

Is AP-BDZ back on line ?

[AM]

BDZ is not back in line and will not be until conclusion of inquiry.As per CVR notwithstanding the technical malfunction of incorrect capts airspeed indicator reading there is complete lack of dicipline and CRM.The crew had standby and F/O altimeters why did capt base his input on his own side instrument .The aircraft landed at a high speed unnecessarily as the capt thought his speed was too low while it was too high.Where was dead reckoning and feel of landscape motion while on approach.His landing caused more damage than the incident was.The capt admonished the first officer in the cvr ,why did you pull the throttles back and the poor fellow replies sir we were too fast.

[FMC]

A310 simulator is now based at Karachi. Training and CRM should not be a problem anymore.

[INSIDER]

Where was dead reckoning and feel of landscape motion while on approach.

Feel of Landscape ............... i love the intelligent remark