Maintenance faulted in 2005 Chalk’s crash

AINalerts » July 5, 2007
July 5, 2007, 12:27 PM

The crash of a Chalk’s Ocean Airways Grumman G-73T Turbo Mallard on Dec. 19, 2005, was due to failure of the amphibian’s right wing. According to the NTSB, the wing separated because of “the failure of the Chalk’s Ocean Airways maintenance program to identify and properly repair fatigue cracks in the right wing and…the failure of the Federal Aviation Administration to detect and correct deficiencies in the company’s maintenance program.” The G-73T is a Mallard modified with Pratt & Whitney Canada turboprop engines and additional passenger seating.

The NTSB held a public meeting on May 30 to discuss the probable cause statement, conclusions and recommendations stemming from the Chalk’s accident. The final report on the accident will not be released until the NTSB makes revisions to the report. The Safety Board has released factual material from its investigation of the accident. Two pilots and 18 passengers were killed after the right wing broke off the Mallard shortly after takeoff near the Port of Miami, Fla., for a flight to Bimini, Bahamas.

The cause of the right wing failure, according to the NTSB, was “pre-existing fatigue fractures and cracks in the rear Z-stringer, lower skin and rear spar lower spar cap.”

At the public meeting, NTSB investigator- in-charge Bill English noted that the accident airplane had flown about 31,000 hours and logged nearly 40,000 flight cycles. “Major structural components in this area as well as others were found to have numerous pre-existing fatigue cracks,” he said during his presentation at the public meeting.

“As these cracks developed, likely over the course of years, they were manifested by fuel leaks and other repeated discrepancies. The repairs that Chalk’s applied to the aircraft were ineffective, literally stopgap measures that did not correct the underlying damage, and the cracks continued to propagate, leading to the catastrophic failure of the wing.”

An Unexplained Repair
Specific problems found during the NTSB investigation included improperly driven rivets on a right wing stringer repair dated July 6, 2000; the installation of a 3/16-inch diameter rivet through the wing skin where the skin and stringer meet at a fuel slosh hole (the skin was also cracked through the rivet hole); and rib-to-stringer interface repairs with angles (aluminum bent to match the underlying structure) and blind rivets that were not documented in engineering drawings for repairs or an FAA Form 337 (used to document major repairs).

A doubler repair on the right wing, in which a cracked portion of skin was sandwiched between two fresh pieces of aluminum intended to strengthen the cracked skin, had “workmanship issues,” according to the NTSB. Investigators were unable to locate maintenance documentation for this particular repair. Flaws with the doubler repair included inadequate rivet edge-distance per FAA-accepted standards; “figure 8 holes” (double-drilled holes) in the right rear spar cap; and other rivet installation imperfections.

No one the NTSB interviewed was able to recall this particular repair or pinpoint when this repair occurred, including Chalk’s maintenance supervisor Juan Heredia, who had worked for the company for 28 years before the accident. According to the NTSB, “Mr. Heredia did not recall doing the repair nor instructed any sheet metal mechanics to accomplish the repair. He recalled seeing the repair several times during the airplane’s C3 inspection (heavy right wing inspection). He stated, ‘It must have been done prior to Chalk’s getting the airplane.’

“Mr. Heredia does not recall seeing any maintenance paperwork for this repair. Furthermore, Mr. Heredia was asked whether any further work was done at the area of the repair. Mr. Heredia recalled one occasion where an external panel had to be resealed due to a fuel leak. Mr. Heredia was then shown numerous stop drills in the major repair area. Mr. Heredia stated that this was the first time he had seen the stop drills. To his recollection he had not instructed any of his mechanics to accomplish an external stop drill repair in that area. Mr. Heredia also noted that the repair looked illegal and did not have the best maintenance practices. “Mr. Heredia further noted that he had never been inside nor had he instructed any of his mechanics to go inside the tank to accomplish any repairs in the vicinity of the repair in question.”

The issue of right wing fuel leaks received major focus in the NTSB’s investigation of this accident. “Because the fuel tank is integral to the structure, any crack in the structure is going to lead to a fuel leak if it’s in the fuel tank area,” said NTSB materials group chairman Matt Fox. “So these repeated fuel leaks are an indication of potential structural problems.”

While the NTSB acknowledged that “no evidence from the performance or appearance of the airplane…would have provided warning to the flight crew of the wing’s imminent failure,” the report contained numerous references to pilots’ complaints about fuel leaks.

“There was a big pilot concern about fuel leaks and why they were happening,” wrote an NTSB investigator summarizing an interview with former Chalk’s pilot Eric Weber. The report noted that Weber “resigned from Chalk’s on Feb. 22, 2005, and his resignation involved issues of maintenance. He experienced three in-flight engine failures, was aware of two in-flight elevator failures involving other company pilots and had concerns about zero fuel weight issues and the overall condition of the airplanes.

“Most fuel leaks that he saw were located at the seam of the right wing on a regular rivet line under the right tank, while other leaks were at the wing root. There was a pocket where the wing and fuselage meet, where the fuel cock is located, and fuel leaks were generally in that area. It was difficult to determine the location of the actual leak as fuel pooled and ran down this area. He had actually seen dripping fuel during preflight inspection, usually in a puddle on the ground in the wheel well region.

“He left Chalk’s because of maintenance concerns. He did not have another job lined up at the time he resigned.”

Capt. Grady Washatka also left Chalk’s because of maintenance concerns, according to the NTSB. Washatka indicated, “If there is something wrong with an aircraft, regardless of whether you can ‘deal with it’ or not, you have a moral and professional obligation not to fly with it…Leaks don’t get smaller. No matter how small that fuel leak is, you don’t know how bad it can get, where it’s coming from or where it might ignite.”

Complacency a Factor
He wrote that in another situation, with aptain Jai Guidry at the controls, one of the Mallards suffered an elevator cable failure after takeoff at 1,000 feet asl. Washakta noted, “You [director of operations Roger Nair] said you believed [Guidry] had gotten water in his bilge and was simply scared of the aircraft rather than there being anything wrong. After that you grabbed your headset and said that you were going to have to fly that airplane out of Nassau for him. After hearing the description of the incident from Jai [Guidry] when he was on the ground, I do not understand how anyone could assume that nothing was wrong with it. None of his reactions tended to indicate fear, yet fear is what was assumed.”

Washakta was also concerned about the Mallards’ airframes and wrote, “The next concern addressed was the numerous cracks and missing rivets in the wings of the aircraft. These cracks and missing rivets had been there for quite some time and whenever the mechanics were questioned about them, their response was either, ‘Yeah, we know about that,’ or simply, ‘Yeah, that’s OK.’ Why the mechanics were unwilling to do necessary and important maintenance on the aircraft is beyond me.”

In his interview with NTSB investigators, Guidry said director of operations Nair told him, “Pilot concerns about cracks would be addressed.” Tracy Perkins, Chalk’s senior maintenance manager, told Guidry that “the cracks were of no concern.”

During the NTSB public meeting and in its probable-cause statement, the Safety Board focused on the FAA’s oversight of Chalk’s maintenance program. “Why this happened was about a different type of failure,” said NTSB vice chairman Robert Sumwalt. “It was a failure of Chalk’s Ocean Airways to identify and properly repair fatigue cracks in the wing, and I think to some extent it’s the failure of the regulatory authority, in this case the FAA, to provide sufficient oversight of this operator. That’s really what the failure is.”

The NTSB faulted the FAA principal maintenance inspector (PMI) for not making sure that major repairs to the accident airplane were properly documented. Although the NTSB noted that the Grumman Mallard was exempt from stringent new FAA aging aircraft inspection and maintenance requirements, it was subject to some aging safety requirements.

On Nov. 4, 2005, FAA inspector Thomas Laird conducted a mandatory FAA aging airplane safety inspection and records review on three Chalk’s Mallards, including the accident airplane. “Discrepancies were noted by the PMI and corrected by Chalk’s Ocean Airways personnel during the combined C5 and C6 inspection performed in November 2005,” according to the NTSB.

“On the airplane in question, he [Laird] looked at the structural write-ups and non-routine work that had been generated during the airplane check. He noted issues with loose rivets, corrosion of the fuselage and surface corrosions. All discrepancies were rectified to his satisfaction.”

Laird had been tasked with overseeing four Part 121 air carriers, one repair station and four Part 125 operators. After January 2005, that workload was reduced to three 121 carriers, including Chalk’s, “due to regional office realignments and his pending retirement,” according to the NTSB.

Professional Airways Systems Specialists (PASS), the union that represents FAA inspectors, is concerned that blaming oversight problems on the FAA ignores the fundamental requirement of an aircraft operator to manage safety. “That’s our number-one concern,” said Linda Goodrich, PASS regional vice president. “Oversight is the responsibility of the airline itself.” At the same time, Goodrich also worries that the FAA is spreading available inspectors over a larger number of operators. Problems with FAA oversight of operators, she said, “are a consequence of diminishing resources.”

Another problem with FAA oversight is that FAA managers might assign low priority to a carrier such as Chalk’s. “They’re very low on the priority list because of the number of flights, the number of passengers and the number of airplanes in the fleet,” Goodrich said. The majority of inspector resources go to the larger airlines with larger fleets, even if the modern large airline may actually be a lower risk operation than a tiny airline flying a handful of 1940s-vintage airplanes in a severe ocean environment. “Logical people didn’t consider that a Mallard could fly in a 121 environment,” Goodrich said.

Goodrich’s observation that a potentially risky operation such as Chalk’s where 60-year-old airplanes with an average of 30,000 hours flying time might be worthy of increased FAA attention is precisely how Loel Fenwick, vice president of the Grumman Mallard Owners Association (GMOA), feels about the aftermath of the Chalk’s accident.

The Chalk’s accident has nothing to do with aging aircraft issues, Fenwick said, but everything to do with “the special requirements of ocean operations.” Any airplane operated in severe conditions will wear out faster, but it doesn’t make sense to extrapolate what happens to that one airplane to an entire fleet operated in a more ordinary fashion.

The accident Mallard had logged 31,226 flying hours over nearly 60 years and almost 40,000 ocean takeoffs and landings. “In addition to finding severe corrosion, widespread cracking and undocumented repairs of the wing structure,” Fenwick wrote in a GMOA statement, “the NTSB investigation also revealed a non-conforming hole drilled through the lower spar cap at the point where the wing failed.” This was the double-drilled or figure-8 holes the Safety Board mentioned in the factual report.

The FAA issued an airworthiness directive after the accident essentially grounding the Mallard fleet (Fenwick owns two piston-powered Mallards). Fenwick formed the GMOA after the accident and, with Mallard type certificate holder Frakes Aviation, has worked with the FAA to develop an alternate means of compliance to keep his and other GMOA members’ Mallards flying.

After performing extensive visual and non-destructive tests of Mallards, Fenwick and the GMOA found that structural deterioration occurs only in Mallards flown in ocean airline operations. “Not a single Mallard that had not been operated in the ocean had any signs of cracking or corrosion,” he told AIN.

Seven Mallards are currently flying under a temporary FAA allowance, which Fenwick hopes to make permanent. No Mallards are currently flying commercially in the U.S., he said, but three are doing so in Australia.

The Mallard, according to Fenwick, was one of the first airplanes to be certified under CAR 4 transport category regulations. “It was never intended to be an airliner,” he said. Grumman “marketed it as the ultimate executive transport.”

After the accident, Fenwick and GMOA members opened up their airplanes by removing the leading-edge cuff on the wing and internal access panels inside the fuel tanks. “We were able to [see] every part of the Mallard center section,” he said. The important result of these detailed inspections was that GMOA members were able to see a consistent pattern of damage in ocean-operated Mallards. “It demonstrated to us,” Fenwick said, “if they are run under those conditions, how they will give ample warning. If you know where to look, you can be sure to catch it.”

GMOA submitted comments to the NTSB investigation and recommendations for safe operation of Mallards. As long as they are managed appropriately for the operating conditions, Fenwick noted, “We have no objection to any legal operation of the airplane.” This means that operators should strictly observe the Mallard flight manual’s 2.5-foot wave-height limitation, carefully monitor and treat corrosion and measure loads caused by hard takeoffs and landings resulting from ocean operations.

“The Mallard flies so well,” Fenwick said, “it’s well balanced and handles beautifully and is incredibly rugged. The first time I saw how Grumman put it together, so amazingly detailed and well thought out, I set out to own Grumman seaplanes.” GMOA welcomes members who want to share all of its hard-won data and will continue helping make sure Mallard parts are available and the airplanes are operated as safely as possible.

GMOA is also considering petitioning the NTSB to amend its findings to take into account the way Chalk operated its Mallards. “We would like the NTSB to look beyond the maintenance of the airplane to consider why the Mallards required that degree of maintenance,” Fenwick said. The Chalk’s fleet doesn’t necessarily represent “a valid data point from which to extrapolate conclusions about airplanes with an entirely different kind of operational history.”

Airline Challenges Pilot Concerns
Chalk’s Ocean Airways also took advantage of the opportunity to provide input to the NTSB and criticized some aspects of the investigation. Chalk’s maintains it is unfair that the NTSB didn’t ask the airline how it addressed the issues raised in Washatka’s letter (see box) to the director of operations.

The Chalk’s response also suggests that Washatka didn’t himself experience many of the safety issues that he mentioned. “The absence of this information, and the failure to validate the opinions expressed by Mr. Washatka and the other pilots, leaves the NTSB factual record incomplete,” the airline’s submission stated. The company’s statement also includes quotes from pilots who praised the airline’s maintenance department.

Fuel leaks required repeated attention, according to Chalk’s, because integral fuel tanks must be sealed and the sealant takes at least 24 hours to dry, then the tank is filled with fuel and leak-checked. If that doesn’t work, the entire process is repeated. Leaks might get written up again, the statement suggested, because it can take a few days after the tank is sealed for reoccurrence of the leak. “However, once they are discovered, the sealant process described above is repeated as evidenced by the consecutive work cards referencing fuel leaks,” the company said.

The airline’s main issue with the NTSB probable cause is that the Safety Board should highlight that the right wing failed because of “metal fatigue emanating from the double-drill hole located where the main spar cap broke.” This defect, the origin of which no one at Chalk’s knew, “occurred in an area that was not routinely accessible by [Chalk’s] and other maintenance personnel. The inaccessibility of this area negated the ability of [the company’s] personnel to conduct complete and thorough preventive maintenance and repair to correct potential safety-of-flight issues.”

The area where the double-drilled hole was located, however, is not inaccessible, according to GMOA’s Fenwick, “if you’re sensitized to go look in that area. It does require a mirror and light and a high degree of focused attention to look around the corner and up into that dark hole.” In any case, Fenwick said, the GMOA does not consider that double-drilled hole to be the primary cause of the Chalk’s wing failure. “It probably contributed along with many other issues,” he said, “but the biggest issue is that the airplanes are operated in a saltwater environment where large waves are almost unavoidable, [causing] a very accelerated structural deterioration from corrosion and additional stress.”

Chalk’s assigns some blame to Mallard manufacturer Grumman and current type certificate holder Frakes Aviation (also holder of the turbine engine and passenger seating supplemental type certificates) for what the airline said is “the complete lack of technical support and a maintenance service manual from Grumman and/or Frakes Aviation for thorough and methodical inspections and repairs, especially as it relates to structural metal fatigue.”

The NTSB factual report does not mention whether Chalk’s maintenance personnel tried to work with Frakes to maintain the airline’s Mallard fleet. According to Frakes Aviation, however, COA was available to consult on Mallard maintenance issues. “Frakes Aviation always had the door open for any Mallard operator,” Joseph Frakes, assistant manager, told AIN. “Chalk’s was welcome to contact us for assistance with any Mallard structure and/or maintenance issue at any time.”

Since the accident, Chalk’s has not joined the GMOA, and the status of the airline’s other four Mallards is not known. The airline did fly some passenger flights in its other Mallards right after the accident, but now it is not itself operating any aircraft but “flies” as Chalk’s International Airlines, with flights operated by Bimini Island Air.

All legal claims by passengers and pilots’ families against Chalk’s Ocean Airways were settled last year, according to law firm Motley Rice, which had filed a lawsuit on behalf of captain Michele Marks, who was at the controls of the ill-fated Mallard. “The insurance company tendered its policy limit last year,” said a Motley Rice spokeswoman, and the Marks lawsuit is no longer active.

Maintenance Problems Abound

Before he left Chalk’s capt. Grady Washatka wrote a long (nearly 4,000-word) letter to Chalk’s director of operations Roger Nair dated Jan. 13, 2005, summarizing his concerns with the company:

• “I have heard numerous times, ‘We’ll just have to make up a tag for an old part back there because we don’t have any.’

• “I have repeatedly heard directly from the mechanics that they don’t have the ability to fix a write-up, yet it’s always signed off the next morning.

• “N2969 [the accident Mallard] came out of maintenance Dec. 12, 2004, with oil leaking from the left engine. It was written up at least six times by December 31 and was still not fixed.

• “On Dec. 18, 2004, I had the right main gear down line on the main actuator leak on N2969. This in itself is not unusual, just a small hydraulic leak. The same line, however, again leaked twice on the 23rd, and once on the 24th, 28th and 31st.

• “A few months ago N2969 had a series of three total hydraulic failures involving the same line in the engine nacelle within a month-and-a-half.

• “When the same fuel leak on N142PA is written up four times within three days you might think that maintenance may try to fix the leak. The next day, however, as the captain wrote up the fuel leak for a fifth time he found a rag jammed into the space where the fuel is coming out.

• “I can’t even count how many times the nosewheel shimmy has been written up in N2969, but I know it was written up at least three times by myself and three times by other pilots within a week. After being written two more times the following week it still did not get fixed until you yourself, the director of operations, took it back and wrote up ‘Nosewheel has violent high-speed and low-speed shimmy.’

• “N2969’s number-two engine did not want to start in the mornings after it came out of inspection on December 12. This did not happen every morning; however, it was written up at least two times on different mornings on which it didn’t want to start in the next week-and-a-half. There were other times it happened when the pilot simply conferred with the mechanics about the problem. The mechanics’ solution every morning was simply to turn the boost pump on and attempt consecutive starts without clearing the engine between the starts. Usually on about the third or fourth attempt, the engine would start with muffled explosions of extra fuel between the primary and secondary fuel nozzles firing. The mechanics would then sign off ‘Normal engine start performed.’

• “On Dec. 27, 2004, during a Part 91 flight returning from Paradise to Fort Lauderdale, I personally showed our chief inspector a torque fluctuation of four to five psi during takeoff on N2969’s number-one engine. Upon arriving in Lauderdale I wrote up this fluctuation. The next morning the sign-off was that they could not duplicate it on the ground. This would usually be acceptable; however, I had told the mechanic that he would not be able to duplicate it on the ground because I had just tried to duplicate it on the ground. This lack of respect for a captain’s write-up is unacceptable. The next morning, however, I took the airplane considering it may have been a fluke when it happened. I took off on the 501 and returned when it started fluctuating just after rotation. It was still between a three- and five-psi oscillation. I wrote it up again, noting in the write-up that I could hear the power changes produced by the engine. Ignoring the fact that I could hear the oscillations, they load tested the torque gauge and said the torque gauge was fine and signed it off. Signing an item off twice consecutively without repairing anything is unacceptable.

“I, however, humored them and asked for a mechanic and a test flight. The director of maintenance agreed to come with me on a test flight. Upon completion of this test flight, the director of maintenance volunteered that he saw the fluctuation and added that he saw the Ng and the prop bouncing around a small amount also and said (yes, this is a direct quote), ‘I think we have an air leak.’ I was happy because I believed they would fix it. Once we returned to the hangar, the director of maintenance along with another mechanic and the chief inspector proceeded to swap the torque gauge, which they had previously checked and affirmed was operating normally. Of course, they did this rather than fix the actual problem.”

Washatka noted in his letter that his complaints, rather than leading to satisfactory repairs, resulted in his being branded a scared pilot “to at least one of the [other] pilots…I can see how it may appear to you that I am afraid, but you are simply misinterpreting my actions. I am not afraid of these airplanes. In fact, I trust these airplanes far more than any other airplane I have ever flown. They are truly tanks in the sky, and it is absolutely amazing as to the beating that they can withstand, and do withstand daily.”

Regulatory Changes Needed

While an airline seaplane operating environment is probably the most demanding of any flight operation, the seaplane regulatory environment has not kept up with developments in regular land-based airline operations. This is because there simply aren’t many seaplane air carriers. “At one time large seaplanes were a significant part of air transport,” said Loel Fenwick, vice president of the Grumman Mallard Owners Association. “That has become such a tiny segment, it’s almost become a black hole into which the aircraft industry really didn’t follow. We’re asking the NTSB to consider a finding that the operational specifications, standards and regulations of seaplane operations are not adequate for safety for ocean airline operations [and] to consider that these specifications and regulations be brought to an appropriate level.”

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