New inspection requirement could ground Cessna 441 Conquest IIs

 - May 1, 2008, 12:55 PM
In a situation reminiscent of the dilemma JetStar owners face, a substantial number of Cessna 441 Conquest II twin turboprops could be grounded come September unless modifications are made to the contents and administration of a Cessna program designed to deal with aging-aircraft issues. Cessna, independent service centers, engineering firms and aircraft owners are all examining ways to keep that from happening, but there are significant problems relating to the new Special Inspection Documents (SID) Cessna introduced last June (Revision 16 to the maintenance manual for the 441). The challenges operators encounter as they attempt to comply with the SID could portend what is to come as more OEMs develop aging-aircraft inspection programs (AAIPs).

The Conquest SID calls for all 441s to undergo a substantial and costly initial inspection by September 1, imposes additions to existing phase inspections and limits the aircraft’s useful life to 22,500 hours. At first glance, the mandatory grounding of non-complying 441s seems to apply only to Part 135 charter operators, but a significant number of those aircraft operating under Part 91 could also be affected, depending on their insurance and other requirements. Industry sources told AIN that number could be as high as 90 percent. Approximately 320 of the 362 Cessna 441 Conquest IIs built between 1977 and 1986 remain in service worldwide. The average airframe time of the 441 fleet is 8,000 hours and the typical aircraft flies 294 hours per year, but a few high-time operators in Australia have run up against the life limit and CASA has grounded those airplanes.

The cost of the initial inspection is estimated at between $120,000 and $180,000 and takes eight weeks, depending on what is discovered, according to Russ Williams, vice president of business development for West Star Aviation in Grand Junction, Colo., the nation’s largest independent 441 service center. Before the SID, the most extensive 441 inspection, the Phase 2-3D, typically ran to about $80,000, he said.

The initial SID inspection is extensive and invasive, according to Williams, necessitating removal of the horizontal and vertical stabilizers, flaps, propellers, engines, engine brackets, interior, radome, de-icing boots and landing gear. Removing and replacing the boots, which must be done to check for corrosion under the wing leading edges, accounts for almost $80,000 of the SID initial inspection’s total cost, he said. He estimated that the ongoing costs of complying with additional SID requirements in subsequent Phase inspections, and the addition of more Phase inspections, will add $50 in direct hourly operating costs for 441 owners.

To date, approximately one-third of all 441s have completed the initial SID inspection. But service center capacity, coupled with customer demand to have substantial non-SID related work done to their aircraft while down for the SID, and a lack of some out-of-production parts, suggests that perhaps as many as one-third of all 441s will not meet the September inspection deadline, according to service center sources.

The non-SID work that is typically bundled with the SID includes the installation of glass-panel avionics systems, new auto-pilots, new radios, RVSM, engine overhauls, and new paint and interior. This work, when combined with the SID, is pushing the out-the-door price on some aircraft to more than $1 million.

Owners do not seem to mind spending this much on airplanes that typically have
a market value of $1.2 to $1.7 million, according to Jerry Griffith, a Tulsa, Okla.-based aircraft broker who specializes in the 441. Even with the SID requirements, “The airplane is in tight supply,” he said, citing its speed, range, fuel economy and comparatively low engine maintenance costs as reasons for its enduring popularity.

“When you look at the amount of the investment, operating costs and capability, nothing else will do what this airplane does.”

A 441 with a Dash 10 engine conversion can take six passengers 1,200 nm at speeds up to 300 knots and at an altitude of 35,000 feet. Hourly fuel burns of 75 gallons are commonplace. The Honeywell TPE331 engines have a recommended TBO of 5,000 hours and cost approximately $175,000 to overhaul. These metrics compare favorably to competitors and continue to make the 441 a notably economical airplane to operate, even in an era of spiking fuel prices.

While the SID has driven some 441s onto the market, Griffith estimates that this number is “maybe three or four.” He said that 441s for sale without the SID completed are being discounted by “about $100,000.”

Parts Acquisition
While the 441’s continued popularity, and its owners’ resultant appetite for upgrades, has slowed the SID process, so has a shortage of some critical parts and Cessna’s continuing reluctance to surrender the Conquest parts business to others, according to several independent service-center managers.

For example, while the SID is supposed to rely on non-destructive testing, removing corrosion from certain parts, such as the main landing-gear axles, can take them out of the fit tolerance for compliance. Replacement gear axles are not currently available, according to Joe Kendrick, West Star’s Conquest program manager. Kendrick said that Cessna has agreed to allow inspection of the gear axles to be deferred until axles become available, but he said the problem is indicative of a larger issue that, in several areas, the SID is flawed. “Cessna is going to have to rewrite the plan,” he said.

Parts have not been a major issue on 441s that have already completed the initial SID inspection, according to Steve Howard, Cessna’s manager of field service for propeller aircraft. “There have been a few fuselage stringers, a couple of emergency exit window repairs and a few horizontal stabilizer reviews,” he told AIN. As the service centers “find issues, we’re working those issues through our engineering repair group to develop engineering repair information,” he said. “Our main concern is corrosion related to the age–25 to 30 years–of these airplanes,” he said.

However, Howard’s disclaimer about parts seems to conflict with what Cessna has told some service centers, according to one service-center manager. “Their official position on parts, as of two months ago, was, ‘If we make the part, we will sell you the part. If we don’t make the part, we won’t tool up for it, we won’t engineer it and you are on your own.’”

Kendrick told AIN that West Star was forced to fabricate its own seat rails when it could not obtain replacements from Cessna.

According to Ben White, director of engineering at Aero Flite, a company that has fashioned contract engineering solutions related to the Conquest SID, the problem extends to engineering as well. White, who previously worked at Cessna as an engineering specialist on the 441, said the SID omits an important issue related to horizontal stabilizer repair that, so far, has affected about a dozen airplanes. During the early 1980s, Cessna replaced all 441 horizontal stabilizers after the flutter-induced in-flight breakup of an early production aircraft. The program affected nearly 100 airplanes and still stands as one of the largest and most expensive factory field modifications of a business aircraft ever.

The new design featured more ribs and a second spar in the horizontal stabilizer and modification of the tail-cone shelf. The new design used bonded assemblies and spliced plates and called for periodic inspection of the bonds. But production problems led to some stringers being unbonded or partially bonded at the factory. Cessna discovered the issue and used rivets to secure the ribs to the stringers and the splice plates. According to White, the SID does not account for those rivets. Rather, it directs that stabilizers be replaced if the missing bonds are not found.

“The problem is,” said White, “there are no [replacement] stabilizers out there.”

So Aero Flite wrote the FAA 8110 engineering order, had it approved by an FAA Designated Engineering Representative (DER) and incorporated it into a major 337 repair as approved by the local FSDO. “Our study allows the rivets as part of a field of fasteners to replace the bonds with rivets. It alters the inspection program and prevented the grounding of at least 12 airplanes out there,” said White, who sees more things like this popping up with the SID. “There are going to be multiple [item] deferrals and multiple revisions. Cessna has things in the works to revise it, and in the meantime is relying on folks like us to keep the airplanes from being grounded.”

White said the stabilizer fix his firm devised added 10 hours of labor and “several thousand dollars” in engineering costs to each aircraft affected. He expects the replacement parts problem will be exacerbated as the SID program matures.

Compliance Extension Possible
Realizing that not all Conquests will be inspected by the September 2008 deadline, Cessna is issuing deferrals on a “case by case” basis that extend up to March 2010. In a statement issued to AIN, Cessna said, “To meet the September 2008 deadline
for the 441 SID inspections due to scheduling conflicts at their authorized service station, Cessna has created an extension program. The length of the extension is based on the schedule availability at the service center of choice.”

Cessna is not granting extensions for aircraft with more than 10,000 hours total time, aircraft that have not had certain past major inspections, are located in coastal areas, or “require an explanation which may or may not be accepted to grant the extension.”

As of the middle of April, Cessna said that it had received 59 extension applications and granted 30 on the first request. Of the 29 not granted, 22 required a horizontal tail inspection first, four needed a routine phase inspection first and three were “flat-out no extension.”

Several service-center managers said that, while the extension process seemed to work well at first, lately it had suffered from “bottlenecks.”

Cessna’s written statement to AIN went on to say that the company was being responsive to 441 owners. “In light of the fact that Cessna has not produced the 441 for 20 years, we’ve been more accommodating than would be expected. The first priority is the safety of our customers and we can’t allow them to fly our aircraft unless they are properly inspected.”

But “properly inspected” may not necessarily mean complying with the SID, according to several service-center and engineering sources.

Aircraft owners operating under Part 91 could conceivably opt out of the SID program if they had an alternative aging-aircraft inspection program approved by their local FSDO.

But having every disaffected aircraft owner develop his own AAIP is in all likelihood costly, impractical and politically untenable. “I can’t imagine that the FAA would support that, after working so hard to get the OEMs to address aging-aircraft issues,” he said.

Aero Flite’s White thinks that eventually all of general aviation will see something like the Conquest SID, “right down to the Piper Cub.” Cessna has already issued SIDs on most of its 300- and 400-series twins and had used a federal grant to develop the research behind the SID on its 402 piston twin.

“As time goes on, we will see this on virtually all aircraft,” said White. “There is a creeping mandate from various directions. Operating rules and design rules are still issues on the regulatory side of this. Cessna has been highly progressive in its application of these things.”

Still, the Conquest SID is just the latest illustration of the special challenges that go with creating a concentrated demand for maintenance, parts and engineering on an aircraft that, while still popular, has been out of production for decades.