PIA Engineering to do Boeing 737-300 lap joint modification

[Abbas Ali]

A PIA Boeing 737-300 - Copyright Dave Campbell

KARACHI, May 9 (APP): National carrier Pakistan International Airlines (PIA) will save 300,000 dollars per aircraft while undertaking in-house Lap Joint Modification of its Boeing 737s.

The Boeing aircraft manufacturing company, during their continual in service research for development had discovered invisible cracks on the Lap Joint areas of Boeing 737 aircraft.

Boeing necessitated modification to the areas identified critical prior to accumulation of 50,000 flight cycles on all Boeing 737 aircraft worldwide.

Boeing 737-300 aircraft were inducted in PIA fleet in 1985 as a regional commuter. Due to short hop flights, frequent take offs and landings, the aircraft accumulated a high number of flight cycles and currently these aircraft are approaching 50,000 flight cycles.

The chairman PIA assigned the airline's Engineering department the task to carry out "Lap Joint Modification".

The department attained the in house capability to accomplish this modification under the guidance of SVP Engineering AVM (Retd) Iftikhar Gul while utilizing his vast experience.

According to PIA sources, modification on the first aircraft is now underway.

PIA said that due to indigenous efforts, PIA would save a considerable amount in terms of labour cost of $100,000 per aircraft while approximate 15 day saving due operation revenue generation will be $200,000. Therefore the total saving per aircraft will be $300,000.

This is yet another milestone in the history of aviation as well as PIA Engineering as the massive undertaking is the first of its kind.

"It speaks volumes of the dedication, skill and workmanship of the engineering staff", PIA said and added that by accomplishing this modification, its Boeing 737 fleet will become revenue generating for the coming years.

After completion of this modification, PIA will be able to market this expertise to other airlines of the world and earn valuable foreign exchange.

Source: Associated Press of Pakistan (May 9, 2006)

On the Net: PIA Engineering

[Abbas Ali]

Fuselage Skin Lap Joint - Fatigue Cracking

Federal Aviation Administration (FAA) Airworthiness Directive Background: The FAA has received a report of a significant number of cracks along the fuselage skin lap joint of a Boeing 737-300 series aircraft. This aircraft had accumulated 35,710 flight cycles. During scheduled maintenance, fatigue cracks were found on a lap joint that extends from aft of the flight deck to the wing front spar just above the passenger windows. Some of the cracks had linked up to form a 10-inch crack. The cracks were attributed to delaminated skin doublers, due to improper processing during phosphoric anodising. The improperly processed panels were installed on certain aircraft during manufacture and were available to other 737 aircraft models as spare parts.
The condition, if not corrected, may result in fatigue cracks in the lap joints and consequent rapid decompression of the aircraft.

Source: Australian Government - Civil Aviation Safety Authority

[Moin]

The engineering dept is now either smacking their foreheads or shitting bricks. I recall them mentioning what a delicate and painstaking process it is. One wrong move or error and its all down the drain.

This could mean 2 things. That they plan to hold onto these a/c for a number of years more and they can get a better resale value on them if they sell them to another airline with this work already carried out.