DHL Express and China-based SF Airlines are most impacted by the discovery of fatigue cracking in Boeing 757-200 aircraft that were converted from passenger to cargo configuration during the past 19 years, according to a FreightWaves analysis.
The Federal Aviation Administration last month issued an airworthiness directive requiring inspections within three months and repair and replacement, where necessary, to the lavatory service panel located on the fuselage bottom of freighters modified by Beaverton, Oregon-based Precision Aircraft Solutions.
The FAA order only applies to 13 aircraft registered in the United States, but 120 aircraft worldwide are affected. Precision Aircraft Solutions has issued a service bulletin to customers on how to resolve the safety issue, but the FAA directive goes further in requiring a fix within about two years. Aviation authorities in other countries could also issue their own directives to airlines based in their jurisdictions.
SF Airlines, the in-house airline of China-based parcel delivery giant SF Express, has 38 757 freighters in its fleet that were converted by Precision Aircraft Solutions. DHL Express has 32 Precision-modified 757 cargo jets, including a handful operated by partner Blue Dart Aviation in India, according to publicly available aviation databases and Precision news releases.
Precision has completed more than 150 conversions for 25 customers around the world. Other airlines with 757 passenger-to-freighter aircraft from Precision include Asia Pacific Airlines (Guam), Cargojet (Canada), Air Transport International (U.S.), Alibaba’s logistics arm Cainiao, Air China Cargo, China Postal Airlines and YTO Cargo Airlines in China. The FAA order applies to Air Transport International and Asia Pacific Airlines since the companies are licensed in the U.S.
“DHL does have a number of aircraft that are subject to the service bulletin issued by Precision Conversions in May regarding inspections and repairs on various 757 aircraft that they converted. We are in close cooperation with Precision and will complete all of the inspections and potential necessary repairs within the time period permitted with little additional cost or downtime to our network,” spokeswoman Pam Duque said in an emailed statement.
The cracks underscore how 757 freighters are legacy aircraft that average more than 27 years of age and transforming a used passenger jet to carry main-deck cargo is a complex engineering process. That effort includes gutting the interior, installing a cargo door and reinforcing the floor and interior walls to support heavy loads.
Early this year, Lufthansa Cargo had to pull from service two Airbus A321 converted freighters so small cracks in rear floor boards could be repaired. The A321s were converted by Elbe Flugzeugwerke GmbH, the aircraft maintenance company owned by Airbus and its engineering partner. They were only 12 and 15 years old, and had been in service with Lufthansa less than two years. EFW said the cracked shear plates found in the rear floor structure during a routine check were unrelated to its conversion work.
The FAA safety directive was prompted by reports of cracking in the structure in and around the access panel covering the service drain to the onboard toilet. The FAA said excessive stress buildup is causing fatigue cracking, which could lead to “significant in-flight depressurization and structural integrity issues if not properly inspected and repaired.”
The agency is requiring operators to repetitively inspect the lavatory service panel, access pan and attaching structure for cracks, reinforce the attaching structure, and, if necessary, replace the access pan or repair cracked parts. Reinforcement must be installed within 2,000 flight cycles after the initial inspection.
Assuming a cargo aircraft conducts 700 to 800 takeoffs and landings annually, it could take two years or more before operators have to do repair work on the freighters.
“Since [certification] in 2005, the 757-200 converted freighter fleet has demonstrated an excellent quality and safety record having accumulated over 1.4 million flight hours and over 750,000 flight cycles. Precision will work with each operator individually to ensure AD compliance in a timely manner with minimal operational disruption,” the engineering firm said in a statement provided to FreightWaves.
The long time frame for completing any necessary repairs means that operators likely will be able to make fixes when aircraft spend one to two weeks undergoing deep maintenance inspections, which usually take place every 20 to 24 months. Under those circumstances, operators probably can minimize any extra downtime. The FAA estimates reinforcement will take about 38 hours to complete.
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